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• What Is an Annotated Bibliography? | Examples & Format

What Is an Annotated Bibliography? | Examples & Format

Published on March 9, 2021 by Jack Caulfield . Revised on August 23, 2022.

An annotated bibliography is a list of source references that includes a short descriptive text (an annotation) for each source. It may be assigned as part of the research process for a paper , or as an individual assignment to gather and read relevant sources on a topic.

Scribbr’s free Citation Generator allows you to easily create and manage your annotated bibliography in APA or MLA style. To generate a perfectly formatted annotated bibliography, select the source type, fill out the relevant fields, and add your annotation.

An example of an annotated source is shown below:

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Table of contents

Annotated bibliography format: apa, mla, chicago, how to write an annotated bibliography, descriptive annotation example, evaluative annotation example, reflective annotation example, finding sources for your annotated bibliography, frequently asked questions about annotated bibliographies.

Make sure your annotated bibliography is formatted according to the guidelines of the style guide you’re working with. Three common styles are covered below:

In APA Style , both the reference entry and the annotation should be double-spaced and left-aligned.

The reference entry itself should have a hanging indent . The annotation follows on the next line, and the whole annotation should be indented to match the hanging indent. The first line of any additional paragraphs should be indented an additional time.

In an MLA style annotated bibliography , the Works Cited entry and the annotation are both double-spaced and left-aligned.

The Works Cited entry has a hanging indent. The annotation itself is indented 1 inch (twice as far as the hanging indent). If there are two or more paragraphs in the annotation, the first line of each paragraph is indented an additional half-inch, but not if there is only one paragraph.

Chicago style

In a  Chicago style annotated bibliography , the bibliography entry itself should be single-spaced and feature a hanging indent.

The annotation should be indented, double-spaced, and left-aligned. The first line of any additional paragraphs should be indented an additional time.

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For each source, start by writing (or generating ) a full reference entry that gives the author, title, date, and other information. The annotated bibliography format varies based on the citation style you’re using.

The annotations themselves are usually between 50 and 200 words in length, typically formatted as a single paragraph. This can vary depending on the word count of the assignment, the relative length and importance of different sources, and the number of sources you include.

Consider the instructions you’ve been given or consult your instructor to determine what kind of annotations they’re looking for:

• Descriptive annotations : When the assignment is just about gathering and summarizing information, focus on the key arguments and methods of each source.
• Evaluative annotations : When the assignment is about evaluating the sources , you should also assess the validity and effectiveness of these arguments and methods.
• Reflective annotations : When the assignment is part of a larger research process, you need to consider the relevance and usefulness of the sources to your own research.

These specific terms won’t necessarily be used. The important thing is to understand the purpose of your assignment and pick the approach that matches it best. Interactive examples of the different styles of annotation are shown below.

A descriptive annotation summarizes the approach and arguments of a source in an objective way, without attempting to assess their validity.

In this way, it resembles an abstract , but you should never just copy text from a source’s abstract, as this would be considered plagiarism . You’ll naturally cover similar ground, but you should also consider whether the abstract omits any important points from the full text.

The interactive example shown below describes an article about the relationship between business regulations and CO 2 emissions.

Rieger, A. (2019). Doing business and increasing emissions? An exploratory analysis of the impact of business regulation on CO 2 emissions. Human Ecology Review , 25 (1), 69–86. https://www.jstor.org/stable/26964340

An evaluative annotation also describes the content of a source, but it goes on to evaluate elements like the validity of the source’s arguments and the appropriateness of its methods .

For example, the following annotation describes, and evaluates the effectiveness of, a book about the history of Western philosophy.

Kenny, A. (2010). A new history of Western philosophy: In four parts . Oxford University Press.

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A reflective annotation is similar to an evaluative one, but it focuses on the source’s usefulness or relevance to your own research.

Reflective annotations are often required when the point is to gather sources for a future research project, or to assess how they were used in a project you already completed.

The annotation below assesses the usefulness of a particular article for the author’s own research in the field of media studies.

Manovich, Lev. (2009). The practice of everyday (media) life: From mass consumption to mass cultural production? Critical Inquiry , 35 (2), 319–331. https://www.jstor.org/stable/10.1086/596645

Manovich’s article assesses the shift from a consumption-based media culture (in which media content is produced by a small number of professionals and consumed by a mass audience) to a production-based media culture (in which this mass audience is just as active in producing content as in consuming it). He is skeptical of some of the claims made about this cultural shift; specifically, he argues that the shift towards user-made content must be regarded as more reliant upon commercial media production than it is typically acknowledged to be. However, he regards web 2.0 as an exciting ongoing development for art and media production, citing its innovation and unpredictability.

The article is outdated in certain ways (it dates from 2009, before the launch of Instagram, to give just one example). Nevertheless, its critical engagement with the possibilities opened up for media production by the growth of social media is valuable in a general sense, and its conceptualization of these changes frequently applies just as well to more current social media platforms as it does to Myspace. Conceptually, I intend to draw on this article in my own analysis of the social dynamics of Twitter and Instagram.

Before you can write your annotations, you’ll need to find sources . If the annotated bibliography is part of the research process for a paper, your sources will be those you consult and cite as you prepare the paper. Otherwise, your assignment and your choice of topic will guide you in what kind of sources to look for.

Make sure that you’ve clearly defined your topic , and then consider what keywords are relevant to it, including variants of the terms. Use these keywords to search databases (e.g., Google Scholar ), using Boolean operators to refine your search.

Sources can include journal articles, books, and other source types , depending on the scope of the assignment. Read the abstracts or blurbs of the sources you find to see whether they’re relevant, and try exploring their bibliographies to discover more. If a particular source keeps showing up, it’s probably important.

Once you’ve selected an appropriate range of sources, read through them, taking notes that you can use to build up your annotations. You may even prefer to write your annotations as you go, while each source is fresh in your mind.

An annotated bibliography is an assignment where you collect sources on a specific topic and write an annotation for each source. An annotation is a short text that describes and sometimes evaluates the source.

Any credible sources on your topic can be included in an annotated bibliography . The exact sources you cover will vary depending on the assignment, but you should usually focus on collecting journal articles and scholarly books . When in doubt, utilize the CRAAP test !

Each annotation in an annotated bibliography is usually between 50 and 200 words long. Longer annotations may be divided into paragraphs .

The content of the annotation varies according to your assignment. An annotation can be descriptive, meaning it just describes the source objectively; evaluative, meaning it assesses its usefulness; or reflective, meaning it explains how the source will be used in your own research .

A source annotation in an annotated bibliography fulfills a similar purpose to an abstract : they’re both intended to summarize the approach and key points of a source.

However, an annotation may also evaluate the source , discussing the validity and effectiveness of its arguments. Even if your annotation is purely descriptive , you may have a different perspective on the source from the author and highlight different key points.

You should never just copy text from the abstract for your annotation, as doing so constitutes plagiarism .

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Annotated Bibliography

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An  annotated bibliography  is a list of citations for various books, articles, and other sources on a topic. The annotated bibliography looks like a References page but includes an annotation after each source cited. An annotation is a short summary and/or critical evaluation of a source. Annotated bibliographies can be part of a larger research project, or can be a stand-alone report in itself.

Basic Tips on Formatting

• Start with the same format as a regular References list.
• The first line of the citation starts at the left margin and subsequent lines are indented 0.5 inches (hanging indent).
• The annotation begins on a new line and is indented 0.5 inches from the left margin.
• Entries are double-spaced with no extra lines between entries.
• If the annotation consists of more than one paragraph, indent the first line of each successive paragraph an additional 0.5 inches.
• Use the third person (e.g., he, she, the author) instead of the first person (e.g., I, my, me).

Sample Evaluative Annotation

Maak, T. (2007). Responsible leadership, stakeholder engagement, and the emergence of social capital.  Journal of Business Ethics ,  74 , 329-343. https://doi.org/10.1007/s10551-007-9510-5

This article focuses on the role of social capital in responsible leadership. It looks at both the social networks that a leader builds within an organization, and the links that a leader creates with external stakeholders. Maak’s main aim with this article seems to be to persuade people of the importance of continued research into the abilities that a leader requires and how they can be acquired. The focus on the world of multinational business means that for readers outside this world many of the conclusions seem rather obvious (be part of the solution not part of the problem). In spite of this, the article provides useful background information on the topic of responsible leadership and definitions of social capital which are relevant to an analysis of a public servant.

Useful Links for Annotated Bibliographies

The formatting of annotated bibliographies can vary. The University Libraries recommend the format exhibited in the examples below, but if you are still unsure what format to use, ask your professor. 

• Includes a sample of one APA annotation (from the Purdue OWL).
• A guide covering the basics of writing an annotated bibliography.
• << Previous: Reference List and Sample Papers
• Next: Citation Software >>

How to Write an Annotated Bibliography - APA Style (7th Edition)

What is an annotation, how is an annotation different from an abstract, what is an annotated bibliography, types of annotated bibliographies, descriptive or informative, analytical or critical, to get started.

An annotation is more than just a brief summary of an article, book, website, or other type of publication. An annotation should give enough information to make a reader decide whether to read the complete work. In other words, if the reader were exploring the same topic as you, is this material useful and if so, why?

While an abstract also summarizes an article, book, website, or other type of publication, it is purely descriptive. Although annotations can be descriptive, they also include distinctive features about an item. Annotations can be evaluative and critical as we will see when we look at the two major types of annotations.

An annotated bibliography is an organized list of sources (like a reference list). It differs from a straightforward bibliography in that each reference is followed by a paragraph length annotation, usually 100–200 words in length.

Depending on the assignment, an annotated bibliography might have different purposes:

• Provide a literature review on a particular subject
• Help to formulate a thesis on a subject
• Demonstrate the research you have performed on a particular subject
• Provide examples of major sources of information available on a topic
• Describe items that other researchers may find of interest on a topic

There are two major types of annotated bibliographies:

A descriptive or informative annotated bibliography describes or summarizes a source as does an abstract; it describes why the source is useful for researching a particular topic or question and its distinctive features. In addition, it describes the author's main arguments and conclusions without evaluating what the author says or concludes.

For example:

McKinnon, A. (2019). Lessons learned in year one of business.  Journal of Legal Nurse Consulting ,  30 (4), 26–28. This article describes some of the difficulties many nurses experience when transitioning from nursing to a legal nurse consulting business. Pointing out issues of work-life balance, as well as the differences of working for someone else versus working for yourself, the author offers their personal experience as a learning tool. The process of becoming an entrepreneur is not often discussed in relation to nursing, and rarely delves into only the first year of starting a new business. Time management, maintaining an existing job, decision-making, and knowing yourself in order to market yourself are discussed with some detail. The author goes on to describe how important both the nursing professional community will be to a new business, and the importance of mentorship as both the mentee and mentor in individual success that can be found through professional connections. The article’s focus on practical advice for nurses seeking to start their own business does not detract from the advice about universal struggles of entrepreneurship makes this an article of interest to a wide-ranging audience.

An analytical or critical annotation not only summarizes the material, it analyzes what is being said. It examines the strengths and weaknesses of what is presented as well as describing the applicability of the author's conclusions to the research being conducted.

Analytical or critical annotations will most likely be required when writing for a college-level course.

McKinnon, A. (2019). Lessons learned in year one of business.  Journal of Legal Nurse Consulting ,  30 (4), 26–28. This article describes some of the difficulty many nurses experience when transitioning from nursing to a nurse consulting business. While the article focuses on issues of work-life balance, the differences of working for someone else versus working for yourself, marketing, and other business issues the author’s offer of only their personal experience is brief with few or no alternative solutions provided. There is no mention throughout the article of making use of other research about starting a new business and being successful. While relying on the anecdotal advice for their list of issues, the author does reference other business resources such as the Small Business Administration to help with business planning and professional organizations that can help with mentorships. The article is a good resource for those wanting to start their own legal nurse consulting business, a good first advice article even. However, entrepreneurs should also use more business research studies focused on starting a new business, with strategies against known or expected pitfalls and issues new businesses face, and for help on topics the author did not touch in this abbreviated list of lessons learned.

Now you are ready to begin writing your own annotated bibliography.

• Choose your sources - Before writing your annotated bibliography, you must choose your sources. This involves doing research much like for any other project. Locate records to materials that may apply to your topic.
• Review the items - Then review the actual items and choose those that provide a wide variety of perspectives on your topic. Article abstracts are helpful in this process.
• The purpose of the work
• A summary of its content
• Information about the author(s)
• For what type of audience the work is written
• Its relevance to the topic
• Any special or unique features about the material
• Research methodology
• The strengths, weaknesses or biases in the material

Annotated bibliographies may be arranged alphabetically or chronologically, check with your instructor to see what he or she prefers.

Please see the  APA Examples page  for more information on citing in APA style.

• Last Updated: Aug 8, 2023 11:27 AM
• URL: https://libguides.umgc.edu/annotated-bibliography-apa

Home / Guides / Citation Guides / Citation Basics / Annotated Bibliography Format & Examples

Annotated Bibliography Format & Examples

A complete guide to the mla & apa annotated bibliography.

If you’ve just received an assignment that requires an MLA or APA annotated bibliography, you may be wondering where to start. This guide will help answer all of your questions and includes step-by-step instructions on how to do an annotated bibliography in MLA style, as well as an APA annotated bibliography. You will also find sample annotated bibliographies, real-life examples, and opportunities to practice what you have learned.

The MLA ( Modern Language Association ) and APA (American Psychological Association) are not associated with this guide. All of the information provided here, however, offers direction for students and researchers who use these citation styles in their work.

The structures and annotated bibliography templates on this page were created by the in-house librarians at EasyBib.com.

If you’re simply looking for an example of an annotated bibliography (both in MLA format and APA format), scroll down toward the bottom of the page. We’ve included links to visuals for those of you who need help with the structure and styling of an annotated bibliography. If you’re looking for a variety of annotated bibliography topics, and you’re truly searching for the answer to, “What is an annotated bibliography?” then continue reading!

Here’s a run-through of everything this page includes:

Table of contents

What is an annotated bibliography, annotations vs. abstract, why include annotations.

• Step 1: Analyze your sources

Step 2: Write the descriptions

• Step 3a: Formatting an MLA style annotated bibliography
• Step 3b: Formatting an APA style annotated bibliography

Annotated Bibliography Templates

Using the easybib annotation tool.

A bibliography is a complete list of the sources that were used to complete a research paper or project.

Depending on the style guide you follow, you may also see this called a Works Cited (also called an MLA bibliography) or Reference List (APA format). Each listed source, or citation , shares information about the author, title, publishing year, and other details that serve to credit the original authors whose work informed your research. These details also help other students and researchers find and read the source materials.

When your research is related to a scholastic assignment, you should always verify your instructor’s requirements for the types and number of sources to include, as well as the style you should adhere to when formatting your paper and bibliography.

An MLA annotated bibliography and an APA format annotated bibliography are bibliographies that include a concise explanation, or annotation , of each listed source. Depending on the assignment, this annotation may be solely descriptive, or analytical.

An abstract and annotation should not be confused; they differ in both their substance as well as their placement in a paper.

Annotations: 

• Usually found in bibliographies at the end of a paper
• Are subjective
• Purpose is to summarize and evaluate . It should briefly communicate the work’s main point, but also discuss the background of the author or study, and the strengths/weaknesses of the work.

Abstracts: 

• Usually found in journal databases or the beginning of a paper
• Are objective
• Purpose is to summarize . It should provide a short overview of the article and communicate the main points and themes.

If you would like to learn more , this link further explores the difference between an abstract and an annotation.

This resource provides additional information on how to write a bibliography with annotations in other formats. You can also take advantage of the plagiarism checker and bibliography tools that come with EasyBib Plus to help you create your reference lists.

Before you learn how to make an annotated bibliography, you may be wondering why you need to.

Sometimes instructors want you to create and include annotations in your bibliography, either as part of an assignment or as an assignment unto itself. Understanding the purpose of this approach to your reference list can help to ensure that you gain all of the benefits that the annotated bibliography process provides.

As a student, this method will help you develop or hone your research skills, providing you with practice not only in locating sources but also in analyzing and evaluating them for relevance and quality.

Your instructor will gain insight into your research abilities, as well, allowing them to assess your work more thoroughly. If you plan to publish your research, this comprehensive approach to detailing your sources will provide readers and other researchers with a substantial directory of resources to evaluate for their own work.

Whether you’re publishing or submitting your annotated bibliography, make sure your spelling and wording is correct! If you need to brush up on any parts of speech topics, check out our interjection , determiner , and adverb pages!

Step 1: Analyze your sources 

Each annotation should be a summarization or analysis of your source. If you have been tasked with writing annotations as part of a research paper or project, begin to create both the citation and notes on the source while you identify and analyze your sources.

Not only will this approach help you to hone your research skills and identify sources that are relevant and useful for your topic, but you will also save time. When done in this manner, both your citations and annotations will be nearly complete before you begin to write the body of your paper.

Analyzing your potential sources requires a two-pronged approach that first evaluates the author, publication, and date, and then examines the content.

When conducting your initial assessment of the source, consider some of the following questions to guide your appraisal:

• What qualifies the author to write on this subject?
• Is the author affiliated with a reputable institution in this field?
• Is the author credentialed or otherwise considered an expert in this field?
• Is this source current?
• Is this the most recent edition?
• Is the publisher reputable?
• Is the journal reputable?

Once your primary evaluation is complete, you will move on the assessing the content itself. Consider some of these elements as you review each source:

• Who is the intended audience?
• Is the author presenting her opinion or interpretation as the truth, or stating facts?
• What supporting evidence does the author provide?
• Did the author perform the research, or curate and present the research of others?
• If the author used the research of others, are the sources the author cites credible?
• Are there errors or omissions of fact?
• Is the author writing objectively and without bias?

Also, consider the value each source provides to you:

• Is the information helpful for your particular assignment?
• Does it help answer your research question(s)?
• Is this source different from your other sources, or does it repeat information you already have?
• Is the source providing you with a different perspective on your topic, or changing your beliefs or thinking about your subject?

To make it easier for you to create your reference page, write your notes in the format you will be using when you construct this part of the assignment (for instance, as short phrases or complete sentences). Once you have identified all of the sources you wish to include, you will merely need to insert what you have already written on the page and write your citation, which is explained in the next section.

Click here for additional information and a supplementary annotated bibliography sample. For an MLA bibliography example (with annotations),  check out our visual example of an MLA annotated bibliography .

An annotated bibliography entry may be written either as short phrases or complete sentences. Your instructor will advise you of which approach you are required to take.

Annotations should include either:

• The main points from the source, as well as the topics covered, the approach used, and any findings.
• Or your critical evaluation.
• A standard annotation is approximately one paragraph.
• Take care not to include any unnecessary details, as the goal is to summarize each source as succinctly as possible and, in some cases, evaluate them.
• Your field of study or instructor will determine what format your annotated bibliography will use. In this guide, you’ll find examples of an MLA and an APA annotated bibliography.

Here is an annotated bibliography example MLA annotation for the book The Elements of Eloquence: Secrets of the Perfect Turn of Phrase by UK author and blogger Mark Forsyth:

The author, Mark Forsyth, examines the rhetorical devices used in the English language, analyzing the patterns and formats that create memorable quotes. He traces the history of rhetoric to the Ancient Greeks, and provides an abridged timeline, following their use and evolution through to modern day. The author also explores the broader subject of persuasion and maps out the role that the figures of rhetoric play in it. In all, he examines over thirty devices, dissecting notable passages and phrases from pop music, the plays of William Shakespeare, the Bible, and more to explore the figures of rhetoric at work within each of them. Thorough definitions accompany this examination of structure to demonstrate how these formulas have been used to generate famously memorable expressions as well as how to reproduce their effects.

Notice how the annotated bibliography MLA entry above is descriptive enough so the reader has an idea of what the source is about with just a single paragraph. For more information on annotations, check out this informative site . If you’re looking to strengthen your writing in general, reading these grammar guides could be a good start.

For guidance on creating entries in MLA format , APA format , and more styles , check out the EasyBib library of resources or try the EasyBib annotation tool—we talk about it below!

Step 3a: MLA annotated bibliography format

The MLA Style Center and the current edition of the MLA Handbook provide the following guidance for formatting an MLA annotated bibliography:

• Title your reference page as “Annotated Bibliography” or “Annotated List of Works Cited.”
• Place each annotation after its reference.
• Annotations should typically not exceed a single paragraph.
• Annotations should be indented one inch from the start of your citation.
• Double-space all text on the page.
• 1-inch margins around the page.

Sources in an annotated bibliography can be organized alphabetically by the first word in each reference (as with a normal Works Cited page), by publication date, or by subject.

For a visual example of an annotated bibliography, as well as specific annotation examples, visit the MLA annotated bibliography guide .

If you are required to share your references in a manner other than in MLA bibliography format, the EasyBib style guides can help you with many common styles. While you’re at it, check out their conjunction , preposition , and pronoun pages to help keep your paper in mint condition!

Step 3b: APA annotated bibliography format

The American Psychological Association states that your instructor should set the guidelines for your annotated bibliography, but asks that the bibliography be formatted according to their standard reference page rules (see Section 9.51 of the Publication Manual ). If your teacher has requested an APA formatted annotated bibliography, first ask them for guidelines. Otherwise, here are some quick rules for you to follow:

• Double space all text on the page.  
• Title your page “Annotated Bibliogra phy”. Bold and center the title.  
• Organize references alphabetically by the first word of each reference.  
• Only the first line of a ref erence is flush with the left margin. Any other lines after the first line should be indented ½ inch from the left.  
• Add annotations on the next line after their paired reference.   
• Fully indent annotations by a ½ inch from the left.  
• Keep annotations short. No more than one paragraph.  

For examples of a  properly formatted APA annotation, visit this guide on APA annotated bibliographies .  

In comparison to the sample annotated bibliography MLA, the APA sample formats its page elements and references differently.

Students and researchers who type their research notes can save time by using an annotated bibliography template in MLA format while reviewing and analyzing sources. By adding the relevant information into a pre-formatted template, you’ll create a resource that helps you when you begin writing your paper in addition to saving time by completing your references and summaries alongside your research.

Students who prefer to take notes by hand can employ a modified version of this approach, with an additional step required to transfer your handwritten and formatted references from your notebook to populate your reference page.

Bibliography Template for MLA

To create an annotated bibliography MLA template, copy the following details into the program in which you will take notes or hand write it on the top margin of a page in your notebook. For each source, use this template to guide you as you identify the necessary details and insert them into your notes:

• Author (Last name, First name).
• Title of source.
• Title of the container ,
• Other contributors (names and roles),
• Publication Date,
• Location of the source (such as URL or page range).
• Summary or Analysis.

The MLA 9 model for MLA works cited entries offers a single format for all source type, and a great deal of flexibility to include the information most relevant to your topic and omit that which isn’t.

Hopefully our visual annotated bibliography example in MLA above has helped. If you still have lingering questions, visit the MLA Style Center online ( linked here ). Also, here’s a guide if you’re looking for more on the related topic of MLA in-text & parenthetical citations .

Bibliography Template for APA

Students and researchers who are still asking themselves how to piece together an annotated bibliography, or still questioning what is an annotated bibliography, could probably benefit from a template, similar to the one above. This one, however, is for those of you who are tasked with creating an annotated bibliography in the style created by the American Psychological Association.

The tricky thing about this specific style though, is that every reference is styled differently. Books, websites, journal articles, newspaper articles, and many others each have their own reference structure.

For most sources though, you should look for the following, basic information:

• Type of source
• Author (last name, first name)
• Title of source/article/web page, etc.
• Title of where source was found (e.g., database name, website name, etc.)
• Other contributors (names and roles)
• Location of the source (such as URL, DOI, or page range)
• Summary or Analysis

We understand it can get tricky, and it’s very different from the Modern Language Association’s structure for references. Take a moment to either use the other handy guides on EasyBib.com or use our automatic generator to form your references in just a few clicks. Our tools help take the pain away from having to rack your brain to form references properly. Capitals, lowercase letters, italics, quotation marks, punctuation in the appropriate places, it can all be quite overwhelming. Do yourself a favor, and use the EasyBib automatic citation generator.

Even though there are a lot of different variations, here’s a commonly used structure for sources:

Author’s Last Name, First initial, Middle initial. (Year the source was published). Title of the source . Retrieved from (insert the website address here)

Underneath the reference, include your summary or analysis paragraph.

Hopefully, this page helped answer all of your “What is an annotated bibliography?” questions. If you’re seeking out an annotated bibliography generator, follow the steps above the annotated bibliography examples.

Looking for additional help with other related topics? Don’t forget about the various beneficial guides on EasyBib.com! Our APA in-text citation guide and our APA parenthetical citation guide are two of our most popular pages. Learn the ins and outs of referencing your work in the body of your paper with our thorough, complete, and reader-friendly guides.

If you are creating a bibliography in MLA format, the EasyBib MLA bibliography generator can help save you time formatting your citations and annotations correctly. You can create entries for websites, books, videos, databases, dictionary articles, and many other types of sources.

In addition to forming the citations, you can also enter your annotation text to produce the complete entry for each source. The process for this is simple. You can follow along below to practice creating one:

• First, select your source type from among the 50+ available options. For this example, we will use the acting career of Keanu Reeves as our research topic and use the movie Point Break from 1991 as our first source. To cite this film, you would select the option for “Film/Online Video.” As you follow along, pick the option that is suitable for your source if you are using a different example.
• Enter the title of your source or, if you are citing a website, you may enter the URL. (Now would be a great time to peek at how to cite websites in MLA ). After you enter the title or URL for your reference, the EasyBib citation tool will scan for titles that match it and provide you with a list of results. Select “Cite this” next to the listing that matches your source.
• You will see a citation form. This gives you the option to add additional relevant or necessary information. For our sample topic, we will specifically cite Keanu Reeves as the performer and Kathryn Bigelow as the director.
• After entering any additional details, you have the option to expand your entry and include an annotation. To do so, select “Add annotation” at the bottom of the page, and a text box will open up.

Then, type your summary or analysis into the text box. If you took notes during the research stage using the format of your paper, this might be as simple as copying and pasting your already written summary or critique. Once you have entered all of the necessary information, select “Create citation” to generate the complete entry. You can then copy and paste this into your MLA bibliography.

Here’s what it’ll look like:

Point Break . Directed by Kathryn Bigelow, performance by Keanu Reeves, 20th Century Fox, 1991.

Reeves’ role as rookie FBI Agent Johnny Utah in Point Break marks the turning point in his Hollywood film career. While he’d risen to fame due to the success of the Bill and Ted franchise, his status today as an action star began when Point Break provided him with the material to establish himself as capable of portraying more than the lovable but unserious characters of his previous starring roles. In a parallel arc, director Kathryn Bigelow’s career also sees a shift beginning with Point Break , establishing her within the traditional action genre as a serious director capable of creating high-action and visually memorable films. While Point Break leaves plenty to be desired in terms of dialogue, it afforded Bigelow and Reeves the opportunities to showcase themselves and their talent in new ways that still echo in their work today.

• Works Cited

Harner, James L.  On Compiling an Annotated Bibliography . 2nd ed., Modern Language Association of America, 2000.

MLA Handbook . 9th ed., Modern Language Association of America, 2021.

Publication Manual of the American Psychological Association . 7th ed., American Psychological Association, 2020.

“What Guidance Should I Give My Students for Preparing an Annotated Bibliography?” The MLA Style Center , The Modern Language Association, 4 Nov. 2016, style.mla.org/annotated-bibliographies/.

Visit our EasyBib Twitter feed to discover more citing tips, fun grammar facts, and the latest product updates.

Published October 18, 2015. Updated July 25, 2021.

Written and edited by Michele Kirschenbaum and Elise Barbeau. Michele Kirschenbaum is a school library media specialist and is the in-house librarian at EasyBib.com. Elise Barbeau is the Citation Specialist at Chegg. She has worked in digital marketing, libraries, and publishing.

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An annotated bibliography is a list containing complete information of sources, such as journals, books, and reports, cited in the text. In addition, it provides a brief description of each source in about 100–150 words. The annotation can explain the topics covered in the source or evaluate the source. The main objective of giving the annotation is to provide the reader the importance, accuracy, and value of the source.

An example of an annotated bibliography in APA style is given below.

Lim, L. (2014). Ideology, rationality and reproduction in education: A critical discourse analysis. Discourse: Studies in the Cultural Politics of Education, 35 (1), 61–76. https://doi:10.1080/01596306.2012.739467

Lim (2014) focuses on issues of power and ideology dominant in curricular discourses of rationality to study a discourse analysis of the goals of one of the most important curricula in the teaching of thinking. He proves that political and class commitments are reproduced in the forms of thinking that are valued in societies. Through his research, Lim asserts that such curricula engage in making our understanding of what thinking and rationality are. It must facilitate the social reproduction of a specific proportion of the middle class.

If you want to evaluate or provide a description of a source you are citing, you can create an annotated bibliography. Write your annotation in 100–150 words and add it below the source for which you are providing your annotation. Remember, your annotation should provide the reader the importance, accuracy, and value of the source. Below are the guidelines and rules to be followed while writing an annotated bibliography for APA style:

Order your reference entries in alphabetical order, similar to how you would order entries in the reference list.

If you want to add an annotation to an entry, add it as a fresh paragraph below the reference entry. The annotation is indented 0.5 inches from the left margin. However, the first line of the annotation is not indented.

To format the annotated bibliography, follow the recommendations given below:

Set the left, right, top, and bottom margins to 1 inch.

Give double-line spacing.

Title the page “Annotated Bibliography.” Set it in bold.

The title should be aligned to the center of the page.

As you format reference entries, left-align all references in the annotated bibliography section. If any entry runs over more than a line, indent the subsequent lines 0.5 inch from the left margin.

Arrange all reference entries alphabetically according to the surname of the authors.

Provide your annotations below the reference entry for which you want to give your annotation. Indent annotations 0.5 inches from the left margin.

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How to Prepare an Annotated Bibliography: The Annotated Bibliography

• The Annotated Bibliography
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Explanation, Process, Directions, and Examples

What is an annotated bibliography.

An annotated bibliography is a list of citations to books, articles, and documents. Each citation is followed by a brief (usually about 150 words) descriptive and evaluative paragraph, the annotation. The purpose of the annotation is to inform the reader of the relevance, accuracy, and quality of the sources cited.

Annotations vs. Abstracts

Abstracts are the purely descriptive summaries often found at the beginning of scholarly journal articles or in periodical indexes. Annotations are descriptive and critical; they may describe the author's point of view, authority, or clarity and appropriateness of expression.

The Process

Creating an annotated bibliography calls for the application of a variety of intellectual skills: concise exposition, succinct analysis, and informed library research.

First, locate and record citations to books, periodicals, and documents that may contain useful information and ideas on your topic. Briefly examine and review the actual items. Then choose those works that provide a variety of perspectives on your topic.

Cite the book, article, or document using the appropriate style.

Write a concise annotation that summarizes the central theme and scope of the book or article. Include one or more sentences that (a) evaluate the authority or background of the author, (b) comment on the intended audience, (c) compare or contrast this work with another you have cited, or (d) explain how this work illuminates your bibliography topic.

Critically Appraising the Book, Article, or Document

For guidance in critically appraising and analyzing the sources for your bibliography, see How to Critically Analyze Information Sources . For information on the author's background and views, ask at the reference desk for help finding appropriate biographical reference materials and book review sources.

Choosing the Correct Citation Style

Check with your instructor to find out which style is preferred for your class. Online citation guides for both the Modern Language Association (MLA) and the American Psychological Association (APA) styles are linked from the Library's Citation Management page .

Sample Annotated Bibliography Entries

The following example uses APA style ( Publication Manual of the American Psychological Association , 7th edition, 2019) for the journal citation:

Waite, L., Goldschneider, F., & Witsberger, C. (1986). Nonfamily living and the erosion of traditional family orientations among young adults. American Sociological Review, 51 (4), 541-554. The authors, researchers at the Rand Corporation and Brown University, use data from the National Longitudinal Surveys of Young Women and Young Men to test their hypothesis that nonfamily living by young adults alters their attitudes, values, plans, and expectations, moving them away from their belief in traditional sex roles. They find their hypothesis strongly supported in young females, while the effects were fewer in studies of young males. Increasing the time away from parents before marrying increased individualism, self-sufficiency, and changes in attitudes about families. In contrast, an earlier study by Williams cited below shows no significant gender differences in sex role attitudes as a result of nonfamily living.

This example uses MLA style ( MLA Handbook , 9th edition, 2021) for the journal citation. For additional annotation guidance from MLA, see 5.132: Annotated Bibliographies .

Waite, Linda J., et al. "Nonfamily Living and the Erosion of Traditional Family Orientations Among Young Adults." American Sociological Review, vol. 51, no. 4, 1986, pp. 541-554. The authors, researchers at the Rand Corporation and Brown University, use data from the National Longitudinal Surveys of Young Women and Young Men to test their hypothesis that nonfamily living by young adults alters their attitudes, values, plans, and expectations, moving them away from their belief in traditional sex roles. They find their hypothesis strongly supported in young females, while the effects were fewer in studies of young males. Increasing the time away from parents before marrying increased individualism, self-sufficiency, and changes in attitudes about families. In contrast, an earlier study by Williams cited below shows no significant gender differences in sex role attitudes as a result of nonfamily living.

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Annotated Bibliographies

What this handout is about.

This handout will explain why annotated bibliographies are useful for researchers, provide an explanation of what constitutes an annotation, describe various types of annotations and styles for writing them, and offer multiple examples of annotated bibliographies in the MLA, APA, and CBE/CSE styles of citation.

Introduction

Welcome to the wonderful world of annotated bibliographies! You’re probably already familiar with the need to provide bibliographies, reference pages, and works cited lists to credit your sources when you do a research paper. An annotated bibliography includes descriptions and explanations of your listed sources beyond the basic citation information you usually provide.

Why do an annotated bibliography?

One of the reasons behind citing sources and compiling a general bibliography is so that you can prove you have done some valid research to back up your argument and claims. Readers can refer to a citation in your bibliography and then go look up the material themselves. When inspired by your text or your argument, interested researchers can access your resources. They may wish to double check a claim or interpretation you’ve made, or they may simply wish to continue researching according to their interests. But think about it: even though a bibliography provides a list of research sources of all types that includes publishing information, how much does that really tell a researcher or reader about the sources themselves?

An annotated bibliography provides specific information about each source you have used. As a researcher, you have become an expert on your topic: you have the ability to explain the content of your sources, assess their usefulness, and share this information with others who may be less familiar with them. Think of your paper as part of a conversation with people interested in the same things you are; the annotated bibliography allows you to tell readers what to check out, what might be worth checking out in some situations, and what might not be worth spending the time on. It’s kind of like providing a list of good movies for your classmates to watch and then going over the list with them, telling them why this movie is better than that one or why one student in your class might like a particular movie better than another student would. You want to give your audience enough information to understand basically what the movies are about and to make an informed decision about where to spend their money based on their interests.

What does an annotated bibliography do?

A good annotated bibliography:

• encourages you to think critically about the content of the works you are using, their place within a field of study, and their relation to your own research and ideas.
• proves you have read and understand your sources.
• establishes your work as a valid source and you as a competent researcher.
• situates your study and topic in a continuing professional conversation.
• provides a way for others to decide whether a source will be helpful to their research if they read it.
• could help interested researchers determine whether they are interested in a topic by providing background information and an idea of the kind of work going on in a field.

What elements might an annotation include?

• Bibliography according to the appropriate citation style (MLA, APA, CBE/CSE, etc.).
• Explanation of main points and/or purpose of the work—basically, its thesis—which shows among other things that you have read and thoroughly understand the source.
• Verification or critique of the authority or qualifications of the author.
• Comments on the worth, effectiveness, and usefulness of the work in terms of both the topic being researched and/or your own research project.
• The point of view or perspective from which the work was written. For instance, you may note whether the author seemed to have particular biases or was trying to reach a particular audience.
• Relevant links to other work done in the area, like related sources, possibly including a comparison with some of those already on your list. You may want to establish connections to other aspects of the same argument or opposing views.

The first four elements above are usually a necessary part of the annotated bibliography. Points 5 and 6 may involve a little more analysis of the source, but you may include them in other kinds of annotations besides evaluative ones. Depending on the type of annotation you use, which this handout will address in the next section, there may be additional kinds of information that you will need to include.

For more extensive research papers (probably ten pages or more), you often see resource materials grouped into sub-headed sections based on content, but this probably will not be necessary for the kinds of assignments you’ll be working on. For longer papers, ask your instructor about their preferences concerning annotated bibliographies.

Did you know that annotations have categories and styles?

Decisions, decisions.

As you go through this handout, you’ll see that, before you start, you’ll need to make several decisions about your annotations: citation format, type of annotation, and writing style for the annotation.

First of all, you’ll need to decide which kind of citation format is appropriate to the paper and its sources, for instance, MLA or APA. This may influence the format of the annotations and bibliography. Typically, bibliographies should be double-spaced and use normal margins (you may want to check with your instructor, since they may have a different style they want you to follow).

MLA (Modern Language Association)

See the UNC Libraries citation tutorial for basic MLA bibliography formatting and rules.

• MLA documentation is generally used for disciplines in the humanities, such as English, languages, film, and cultural studies or other theoretical studies. These annotations are often summary or analytical annotations.
• Title your annotated bibliography “Annotated Bibliography” or “Annotated List of Works Cited.”
• Following MLA format, use a hanging indent for your bibliographic information. This means the first line is not indented and all the other lines are indented four spaces (you may ask your instructor if it’s okay to tab over instead of using four spaces).
• Begin your annotation immediately after the bibliographic information of the source ends; don’t skip a line down unless you have been told to do so by your instructor.

APA (American Psychological Association)

See the UNC Libraries citation tutorial for basic APA bibliography formatting and rules.

• Natural and social sciences, such as psychology, nursing, sociology, and social work, use APA documentation. It is also used in economics, business, and criminology. These annotations are often succinct summaries.
• Annotated bibliographies for APA format do not require a special title. Use the usual “References” designation.
• Like MLA, APA uses a hanging indent: the first line is set flush with the left margin, and all other lines are indented four spaces (you may ask your instructor if it’s okay to tab over instead of using four spaces).
• After the bibliographic citation, drop down to the next line to begin the annotation, but don’t skip an extra line.
• The entire annotation is indented an additional two spaces, so that means each of its lines will be six spaces from the margin (if your instructor has said that it’s okay to tab over instead of using the four spaces rule, indent the annotation two more spaces in from that point).

CBE (Council of Biology Editors)/CSE (Council of Science Editors)

See the UNC Libraries citation tutorial for basic CBE/CSE bibliography formatting and rules.

• CBE/CSE documentation is used by the plant sciences, zoology, microbiology, and many of the medical sciences.
• Annotated bibliographies for CBE/CSE format do not require a special title. Use the usual “References,” “Cited References,” or “Literature Cited,” and set it flush with the left margin.
• Bibliographies for CSE in general are in a slightly smaller font than the rest of the paper.
• When using the name-year system, as in MLA and APA, the first line of each entry is set flush with the left margin, and all subsequent lines, including the annotation, are indented three or four spaces.
• When using the citation-sequence method, each entry begins two spaces after the number, and every line, including the annotation, will be indented to match the beginning of the entry, or may be slightly further indented, as in the case of journals.
• After the bibliographic citation, drop down to the next line to begin the annotation, but don’t skip an extra line. The entire annotation follows the indentation of the bibliographic entry, whether it’s N-Y or C-S format.
• Annotations in CBE/CSE are generally a smaller font size than the rest of the bibliographic information.

After choosing a documentation format, you’ll choose from a variety of annotation categories presented in the following section. Each type of annotation highlights a particular approach to presenting a source to a reader. For instance, an annotation could provide a summary of the source only, or it could also provide some additional evaluation of that material.

In addition to making choices related to the content of the annotation, you’ll also need to choose a style of writing—for instance, telescopic versus paragraph form. Your writing style isn’t dictated by the content of your annotation. Writing style simply refers to the way you’ve chosen to convey written information. A discussion of writing style follows the section on annotation types.

Types of annotations

As you now know, one annotation does not fit all purposes! There are different kinds of annotations, depending on what might be most important for your reader to learn about a source. Your assignments will usually make it clear which citation format you need to use, but they may not always specify which type of annotation to employ. In that case, you’ll either need to pick your instructor’s brain a little to see what they want or use clue words from the assignment itself to make a decision. For instance, the assignment may tell you that your annotative bibliography should give evidence proving an analytical understanding of the sources you’ve used. The word analytical clues you in to the idea that you must evaluate the sources you’re working with and provide some kind of critique.

Summary annotations

There are two kinds of summarizing annotations, informative and indicative.

Summarizing annotations in general have a couple of defining features:

• They sum up the content of the source, as a book report might.
• They give an overview of the arguments and proofs/evidence addressed in the work and note the resulting conclusion.
• They do not judge the work they are discussing. Leave that to the critical/evaluative annotations.
• When appropriate, they describe the author’s methodology or approach to material. For instance, you might mention if the source is an ethnography or if the author employs a particular kind of theory.

Informative annotation

Informative annotations sometimes read like straight summaries of the source material, but they often spend a little more time summarizing relevant information about the author or the work itself.

Indicative annotation

Indicative annotation is the second type of summary annotation, but it does not attempt to include actual information from the argument itself. Instead, it gives general information about what kinds of questions or issues are addressed by the work. This sometimes includes the use of chapter titles.

Critical/evaluative

Evaluative annotations don’t just summarize. In addition to tackling the points addressed in summary annotations, evaluative annotations:

• evaluate the source or author critically (biases, lack of evidence, objective, etc.).
• show how the work may or may not be useful for a particular field of study or audience.
• explain how researching this material assisted your own project.

Combination

An annotated bibliography may combine elements of all the types. In fact, most of them fall into this category: a little summarizing and describing, a little evaluation.

Writing style

Ok, next! So what does it mean to use different writing styles as opposed to different kinds of content? Content is what belongs in the annotation, and style is the way you write it up. First, choose which content type you need to compose, and then choose the style you’re going to use to write it

This kind of annotated bibliography is a study in succinctness. It uses a minimalist treatment of both information and sentence structure, without sacrificing clarity. Warning: this kind of writing can be harder than you might think.

Don’t skimp on this kind of annotated bibliography. If your instructor has asked for paragraph form, it likely means that you’ll need to include several elements in the annotation, or that they expect a more in-depth description or evaluation, for instance. Make sure to provide a full paragraph of discussion for each work.

As you can see now, bibliographies and annotations are really a series of organized steps. They require meticulous attention, but in the end, you’ve got an entire testimony to all the research and work you’ve done. At the end of this handout you’ll find examples of informative, indicative, evaluative, combination, telescopic, and paragraph annotated bibliography entries in MLA, APA, and CBE formats. Use these examples as your guide to creating an annotated bibliography that makes you look like the expert you are!

MLA Example

APA Example

CBE Example

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

American Psychological Association. 2010. Publication Manual of the American Psychological Association . 6th ed. Washington, DC: American Psychological Association.

Bell, I. F., and J. Gallup. 1971. A Reference Guide to English, American, and Canadian Literature . Vancouver: University of British Columbia Press.

Bizzell, Patricia, and Bruce Herzburg. 1991. Bedford Bibliography for Teachers of Writing , 3rd ed. Boston: Bedford Books.

Center for Information on Language Teaching, and The English Teaching Information Center of the British Council. 1968. Language-Teaching Bibliography . Cambridge: Cambridge University.

Engle, Michael, Amy Blumenthal, and Tony Cosgrave. 2012. “How to Prepare an Annotated Bibliography.” Olin & Uris Libraries. Cornell University. Last updated September 25, 2012. https://olinuris.library.cornell.edu/content/how-prepare-annotated-bibliography.

Gibaldi, Joseph. 2009. MLA Handbook for Writers of Research Papers , 7th ed. New York: The Modern Language Association of America.

Huth, Edward. 1994. Scientific Style and Format: The CBE Manual for Authors, Editors, and Publishers . New York: University of Cambridge.

Kilborn, Judith. 2004. “MLA Documentation.” LEO: Literacy Education Online. Last updated March 16, 2004. https://leo.stcloudstate.edu/research/mla.html.

Spatt, Brenda. 1991. Writing from Sources , 3rd ed. New York: St. Martin’s.

University of Kansas. 2018. “Bibliographies.” KU Writing Center. Last updated April 2018. http://writing.ku.edu/bibliographies .

University of Wisconsin-Madison. 2019. “Annotated Bibliography.” The Writing Center. Accessed June 14, 2019. https://writing.wisc.edu/handbook/assignments/annotatedbibliography/ .

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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What is an annotated bibliography?

An annotated bibliography is an organized list of sources, each of which is followed by a brief note or “annotation.”

These annotations do one or more of the following:

• describe the content and focus of the book or article
• suggest the source’s usefulness to your research
• evaluate its method, conclusions, or reliability
• record your reactions to the source.

The process of writing an annotated bibliography provides a structured process to learn about a research topic. It causes you to read the available research (also referred to as "the literature") more closely as you develop a better understanding of the topic, related issues, and current trends. 

Source: The University of Wisconsin-Madison: The Writing Center

Writing a strong annotation

The hardest part of this assignment is writing the annotation, but knowing what it entails can make this task less daunting.

While not all of these are necessary, an annotation could/will:

• Summarize the central theme and scope of the document
• Evaluates the authority, credibility, and/or background of the author(s)
• Comments on the intended audience (who was meant to read the document)
• Assesses the source’s strengths and weaknesses (Interesting? Helpful? Strong/weak argument? Strong/weak evidence?)
• Compares or contrast this work with others you have cited
• Critiques the relevance, accuracy, and quality of the source
• Evaluates the methods, conclusions/findings, and reliability of the source
• Shares how the source reinforces or contradicts your own argument
• Records your reactions to the reading
• States how the source will be used in your paper

Source:  UNT Dallas Learning Commons: Annotated Bibliography

Formatting rules

General Formatting Rules:

• Format and order references in alphabetical order just as you would a reference list
• Each annotation should be a new paragraph below its reference entry
• Indent the entire annotation 0.5 inch from the left margins just as you would a block quotation
• If the annotation spans multiple paragraphs, indent the first line of the second and any subsequent paragraphs an addition 0.5 inch the same as you would a block quotation with multiple paragraphs  

Source: Section 9.51 Annotated Bibliographies in the APA 7th Edition Publication Manual

Sample annotated bibliography

Excelsior OWL Sample Annotated Bibliography

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Annotations

An  annotated bibliography  is a list of citations for various books, articles, and other sources on a topic. The annotated bibliography looks like a References page but includes an annotation after each source cited. An annotation is a short summary and/or critical evaluation of a source. Annotated bibliographies can be part of a larger research project, or can be a stand-alone report in itself.

Types of Annotations

 A  summary annotation  describes the source by answering the following questions: who wrote the document, what does the document discuss, when and where was the document written, why was the document produced, and how was it provided to the public. The focus is on description. 

 An  evaluative annotation  includes a summary as listed above but also critically assesses the work for accuracy, relevance, and quality. Evaluative annotations can help you learn about your topic, develop a thesis statement, decide if a specific source will be useful for your assignment, and determine if there is enough valid information available to complete your project. The focus is on description and evaluation.

Writing an Evaluative Annotation

• Cite the source using APA style.
• Describe the main ideas, arguments, themes, theses, or methodology, and identify the intended audience.
• Explain the author’s expertise, point of view, and any bias he/she may have.
• Compare to other sources on the same topic that you have also cited to show similarities and differences.
• Explain why each source is useful for your research topic and how it relates to your topic.
• Evaluate the strengths and weaknesses of each source.
• Identify the observations or conclusions of the author. 

Basic Tips on Writing & Formatting

• Each annotation should be one paragraph, between three to six sentences long (about 150- 200 words).
• Start with the same format as a regular References list.
• All lines should be double-spaced. Do not add an extra line between the citations.
• If your list of citations is especially long, you can organize it by topic.
• Try to be objective, and give explanations if you state any opinions.
• Use the third person (e.g., he, she, the author) instead of the first person (e.g., I, my, me)

Annotated bibliographies are formated in the method below.

Use a hanging indent for any references that are longer than one line.

The text of the annotation (where you explain who wrote the article, what they found, and why it is relevant to your paper) goes in a paragraph that has been indented directly below the reference entry. 

Johnston, M.P. (2013). School librarian & technology specialist: Partnership for effective technology integration. Knowledge Quest , 42 (1), 70-75.

Written by an assistant professor of library and information science and based on her personal experience, observations, and evidence-based research, this article attempts to cement the necessity for open communication between the school librarian and technology specialist. A cohesive relationship with mutual support proves to be a better way for the educational world to navigate the productive use of technology. If librarians and technology specialists are at odds within a school, then the only ones that suffer are the teachers and the students. A cohesive team of media specialists can better serve the school while teaching and integrating new technology in the classroom. Productivity for media specialists, both librarians, and technology specialists, also demands working cohesively with classroom teachers since many need assistance with technology integration. Open communication and consideration are integral to this process and only when these two factors happen in tandem can a school fully realize the possibilities inherent in technology. 

Moreillon, J., (2013). Leadership: Teaching digital citizenship . School Library Monthly , 30 (1), 26-27.

Written by an assistant professor of library and information studies in Texas, this article focuses on digital citizenship. The information, from the author’s personal observations and through discussions with colleagues, highlights the tools librarians currently use to increase their digital clout and technological presence within a school setting and recommends other tools that are potentially available. The author surmises that teaching digital citizenship purposefully helps integrate the correct use of technology while following standards set by the Common Core State Standards. Being advocates for teaching staff and students about digital citizenship acutely brings to focus the need for informed library specialists and the need for adequate technology resources. The author recommends fostering a proactive community in order to help students and staff become informed digital citizens prepared to navigate the wide world of technology.

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APA Guide - 7th Edition: Annotated Bibliographies

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Annotated Bibliography

An annotated bibliography is a type of student paper in which reference list entries are followed by short descriptions of the work, called annotations.  Annotated bibliographies can also constitute one element of a research paper in fields that require bibliographies rather than reference lists.  Most APA Style guidelines are applicable to annotated bibliographies (margins, font, line spacing, etc.).

In general, it is not necessary to cite the work being annotated in the annotations because the origin of the information is clear through context. However, do include in-text citations if you refer to multiple works within an annotation to clarify the source.

Examples & Templates

• Annotated Bibliography Sample from APA Manual
• Annotated Bib Template_Includes Title Page
• How to Create an Annotated Bibliography

What is an Annotated Bibliography?

What is an Annotated Bibliography? by OWLPurdue on YouTube

Useful Links

• Purdue OWL Definitions, formatting, examples, & samples.
• Writing an Annotated Bibliography General guide from the University of Guelph. Overview and examples.

Evaluative Annotations

An evaluative annotation includes a summary but also critically assesses the work for accuracy, relevance, and quality. The focus is on description and evaluation.

They can help you: 

• learn about your topic
• develop a thesis statement
• decide if a specific source will be useful for your assignment
• determine if there is enough valid information available to complete your project. 

Sample Annotation

Basic Writing & Format Tips

Basic Writing and Format Tips:

• Start with the same format as a regular References list.
• After each citation, the annotation is indented two spaces from the left margin as a block.
• Each annotation should be one paragraph, between three to six sentences long (about 150-200 words).
• All lines should be double-spaced. Do not add an extra line between the citations.
• If your list of citations is especially long, you can organize it by topic.
• Try to be objective, and give explanations if you state any opinions.
• Use the third person (e.g., he, she, the author) instead of the first person (e.g., I, my, me).

Annotations

An  annotation  is a summary and/or evaluation. Therefore, an annotated bibliography includes a summary and/or critical evaluation of each of the sources. The annotated bibliography looks like a References page but includes an annotation after each full citation.

Annotated bibliographies can be part of a larger research project, or can be a stand-alone report in itself.

Depending on your project or the assignment, your annotations may do one or more of the following: 

• Some annotations merely summarize the source. What are the main arguments? What topics are covered? The length of your annotations will determine how detailed your summary is.  Who wrote the document? When and where was the document written?
• After summarizing a source, it may be helpful to evaluate it. Is it a useful source? How does it compare with other soruces in your biliography? What is the goal of this source?
• Once you've summarized and assessed a source, ask yourself how it fits into your research. How does it help shape your argument? How can you use this source in your research project?

Your annotated bibliography may include some of these, all of these, or even others. If you're doing this for a class, you should get specific guidelines from your instructor.

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APA annotated bibliography

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An annotated bibliography is a special type of bibliography that provides additional information about the sources listed in the references list. The additional information about a source is called an annotation. An annotation can be given for all types of sources such as journals, books, or reports. The length of the annotation can extend up to 150 words.

Aim of an annotated bibliography

The aim of an annotated bibliography is to either provide details of the topics discussed in the source or assess the source. The primary goal of adding an annotation is to give the reader the significance, merit, and benefit of using a source. Never try to provide proof, take the author’s text verbatim, or discuss irrelevant points in your annotation.

Classification of annotations

Annotations are classified into two types:

Descriptive

The descriptive type gives crucial details of the source or describes the source. It gives insight into the topic covered in the source. It can also explain the purpose of the source.

An evaluative annotation analyzes a source. It explores a source and shows its relevance by examining its preciseness. An evaluative annotation tries to correlate the source with other recognized sources or studies on the same topic. It may also talk about the merits and demerits of a source.

Parts of an annotated bibliography

An annotated bibliography consists of

• The citation
• The annotation

The citation includes all components of a source. For example, the author, book title, publisher, and publication year are important components to be included in a book citation.

Fairclough, N. (2015). Language and power . Routledge.

The annotation provides the necessary fundamental details of the source. As mentioned, the details can be either descriptive or evaluative.

Descriptive annotation

It gives a brief description of all relevant information of the source. The below example is taken from Fairclough (2015). Complete information of the source is given below the annotation.

The book focuses on how language functions in maintaining and changing power relations in modern society, the ways of analyzing language which can reveal these processes, and how people can become more conscious of them, as well as more able to resist and change them. Norman Fairclough includes a substantial new introduction and brings the discussion up to date. He shows both the importance of the book in the development of critical discourse analysis over the past three decades and how language and power relations have changed due to major socioeconomic changes.

Evaluative annotation

An evaluative annotation mirrors the views of the author, highlights the benefits of the work, and also provides a detailed evaluation of the source.

This book of Fairclough is a preamble to the study of discourse analysis. The book shows its steady importance and contribution to language and power. The book clearly illustrates the relationship between language and power with sufficient evidence. The book is important for students pursuing discourse analysis and other related fields.

Rules for creating annotated bibliographies

• The annotation is added after the reference-list entry of a source.
• The annotation extends up to 150 words.
• Both phrases and full sentences are permitted in the annotation.
• Write the annotation in a single paragraph. However, if you want to include multiple paragraphs, indent the second and subsequent paragraphs. However, the paragraphs should not have any extra line spaces in between.

Writing annotated bibliographies

To write an annotated bibliography in APA, follow the below guidelines:

• The annotation should be short and concise.
• Use various links such as “while,” “but,” and “in addition” to connect sentences. This will enhance the readability of your content.
• Do not use words that serve no purpose in your sentences.
• Avoid very long sentences.
• Put forth your views directly.
• Avoid contractions such as “won’t” and ‘isn’t” in the annotation.

Formatting annotated bibliographies

To format an annotated bibliography in APA, follow the below recommendations:

• Begin your annotated bibliography on a new page after the end of the body text.
• The annotated bibliography appears before the figures, tables, and appendices.
• Set the left, right, top, and bottom margins at 1 inch.
• The lines are double-spaced.
• The title should be “Annotated Bibliography.” Format the heading in bold.
• Center align the title to the page.
• All references are aligned left in the annotated bibliography. For entries running over more than a line, provide 0.5 inches indent to the second and subsequent lines from the left margin.
• Entries are arranged according to the alphabetical arrangement of the author’s surnames.
• Each annotation is added below its corresponding reference entry. Annotations are indented 0.5 inches from the left margin.

Arranging annotated bibliographies

There is no need to look at annotations for arranging them. Arrange the reference entries alphabetically per the author’s surname and place the annotation below the corresponding entry.

For references without authors, arrange the entries by their title.

Example annotated bibliography

The below example shows an annotated bibliography:

• Annotated Bibliography

Lim, L. (2014). Ideology, rationality and reproduction in education: A critical discourse analysis. Discourse: Studies in the Cultural Politics of Education, 35 (1), 61–76. https://doi:10.1080/01596306.2012.739467

Lim focuses on problems of power and perception dominant in academic discourses of logic to study a discourse analysis of the goals of the most important subjects in teaching thinking. He proves that social and group responsibilities are reproduced as thinking that is treasured by all in society. Through his research, Lim asserts that such courses retain our understanding of thinking and reasoning. It must enhance the social reproduction of a specific proportion of the normal group of people.

Key takeaways

• An annotated bibliography is a special type of bibliography that provides additional information about the sources listed in the references list.
• The aim of an annotated bibliography is to either provide details of the topics discussed in the source or assess the source.
• The two types of annotations are descriptive and evaluative.
• The heading should be “Annotated Bibliography.”
• Annotation can be written up to 150 words.

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APA 7th Edition Guide: Annotated Bibliography

• General Formatting
• In-Text Citation
• Reference Page
• Reference List Examples

Annotated Bibliography

• APA Video Tutorials

What is an Annotated Bibliography?

A bibliography is a list of references to books, articles, or other items consulted during the research process, while an Annotation is a note of explan ation and evaluation of a particular item being referenced. Therefore, an Annotated Bibliography is a list of references that include an explanatory note below each reference that summarizes and provides an evaluation of the content of the reference.

What is the Benefit of Writing an Annotated Bibliography?

The process of writing an annotated bibliography provides a structured process to learn about a research topic. It causes you to read the available research (also referred to as the literature) more closely as you develop a better understanding of the topic, related issues, and current trends. Time spent writing an annotated bibliography will help you develop a well thought out thesis statement or develop a literature review.

What should an Annotation Include?

A well-written annotation consists of three parts:

• Summary – includes the main points, arguments, and topics covered in the reference being annotated.
• Evaluation – assesses the quality of the source compared to other sources in the bibliography. It may also be important to note the goal, reliability, and objectivity of the reference being annotated.
• Reflection – How does this reference change your understanding of the topic? How will you use the reference in your research? How does the reference affect your thesis? If you do not intend to use the reference in your work then briefly explain why.

How should an Entry to an Annotated Bibliography be Formatted?

Below is an example of how to format a reference and annotation:

GENERAL FORM: Author’s Last Name, Initials, & 2nd Author’s Last Name, Initials. (Year). Title of article: Subtitle of article. Title 

of Journal , volume number (issue), page range. doi: xxx.xxxxx

This is an example of an annotation of a scholarly article. The annotation should be 200 to 300 words

long and include a Summary of the main points, arguments, and topics covered in the reference. Then

you should Evaluate the quality of the source compared to other sources in the bibliography. Your

evaluation may include notes on the goal, reliability, and objectivity of the reference being annotated. 

Then you will want to include a Reflection that covers how the content of the reference changed your

understanding of the topic. How you intend to use the reference in your research? How does the

reference affect your thesis? If you do not intend to use the reference in your work then briefly explain

why. Once you finish writing your annotation go to the next double-spaced line and enter the next entry

of your annotated bibliography .

Hatnik, L., Calloway, S., Joy, N., Owen, F. A., & Constantine, G. A. (2017). Leadership creativity as social

action and transformation: A case study. International Journal of Leadership Studies , 14(3), 72-78.

doi:11.1702/jls.21719

This article presents a case study that addresses the difficulty students have in connecting class content

with real-life social problems. As a potential solution for this problem, students enrolled in a university

course on social, global, and environmental issues worked on a creative project with a charity that aids

women leaving incarceration. The course coupled this community work with class readings, discussions,

and guest speakers, leading students to have a deeper learning experience that also benefited the

target community. While the case study’s conclusions provide potentially helpful information, the authors

neglect to provide any hard evidence for the assumed difficulty in connecting class content to real-life

problems. Furthermore, the authors admit at one point that a few students doubted various aspects of

the class, but this group is not addressed in the conclusions section of the article. Despite a few

shortcomings, the case study does provide a useful strategy that can help young leaders gain real-world

experience which can be adapted to the high school setting I am researching.

How Should an Annotated Bibliography be Formatted using APA 7 th  edition

The format of an annotated bibliography follows the same format as any APA paper.

• Include a title page [See Title Page Setup ]
• Page numbers will begin on the title page and on each page of the annotated bibliography
• Font style and size are the same as any other APA paper [See General Formatting ]
• The order of the references should be in alphabetical order by the lead author’s last name [See Reference Page ]
• Each reference should be formatted in hanging indent paragraph formatting
• The annotation portion should be lined up with the hanging portion of the reference (see the example below)

​ An example of an Annotated Bibliography

Create your own Annotated Bibliography by Downloading this  Annotated Bibliography Template

Download the Annotated Bibliography Format Guide

For information on how to effectively write an annotated bibliography entry go to: 

UNT Dallas Writing Lab Annotated Bibliography

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APA Style Guide, 7th Edition: Annotated Bibliography

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Annotated Bibliography

an•no•ta•tion : n. 1. The act or process of furnishing critical commentary or explanatory notes. 2. A critical or explanatory note; a commentary.

The American Heritage Dictionary of the English Language, 4th ed., Houghton Mifflin, 2009.

What is an Annotated Bibliography?

A list of citations for books, articles, websites, and other materials where each citation is accompanied by a brief descriptive and evaluative statement, called an annotation .

Annotations are different from the abstracts you will find accompanying journal article citations in online databases.  Abstracts are descriptive. Your annotation must extend beyond the descriptive element to include an evaluation of the book or article.

Why Annotations?

An annotated bibliography is a tool for exploring a topic of interest.  The process of reading and reflecting on the materials you find in the gather part of the research process can help you understand the topic, identify multiple perspectives, explore different methods used to investigate the topic, and give you ideas for developing the thesis for your paper.

How are Annotations Created?

• Locate and record the citations for articles, books, and other materials you will use for your paper.  You need to gather enough sources to represent a range of perspectives on your topic.
• Create the citation using the appropriate style (MLA, APA, etc.). Tools that can help you with this include handouts received in class and in the library.
• Write the annotation considering the questions below.  Keep it short but be very complete.

Questions to consider when evaluating the item and writing your annotation include:

• What education, experience and/or background does the author have which contributes to their being an authority on the topic?
• Who is the intended audience for the book or article and how does that influence the presentation of the information?
• How does this work contribute to your argument or support claims about your topic?
• What are the main conclusions of the author(s) and what evidence do they use to support them?

The Publication Manual of the American Psychological Association, 7th edition provides the following basic information for creating an annotated bibliography. 

• Format and order references in an annotated bibliography in alphabetical order, the same as you would order entries in a reference list (see section 9.43 -9.44 of the APA manual)
• Each annotation should be a new paragraph below its reference entry.  Indent the entire annotation 0.5 in. from the left margin, the same as you would a block quotation (see Section 8.27 of the APA manual).  Do not indent the first line of the annotation.
• If the annotation spans multiple paragraphs, indent the first line of the second and any subsequent paragraphs an additional 0.5 in., the same as you would a block quotation with multiple paragraphs.

Figure 9.3 Sample Annotated Bibliography

Annotated Bibliographies. University Libraries, U of Nevada Las Vegas, www.library.unlv.edu/, 2018.

• Example APA Annotated Bibliography Remember, always follow your professor's instructions when creating an annotated bibliography.
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APA Citation Guide (7th edition) : Annotated Bibliography

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Annotated Bibliography Template

• APA Annotated Bibliography Template

This sample annotated bibliography shows you the structure you should use to write an APA annotated bibliography and gives examples of evaluative and summary annotations.

It can be used as a template to set up your assignment.

Useful Links for Annotated Bibliographies

• The Annotated Bibliography APA Overview and examples of an APA annotated bibliography from the CapU Writing Centre.
• Annotated Bibliographies Overview of purpose and form of annotated bibliographies from the Purdue OWL.
• Writing an Annotated Bibliography Overview and examples from the University of Guelph.
• Writing an Annotated Bibliography Definition, tips, and examples from the University of Toronto.

Annotations

An annotated bibliography is a list of citations for various books, articles, and other sources on a topic. The annotated bibliography looks like a Reference page but includes an annotation after each source cited. An annotation is a short summary and/or critical evaluation of a source. An annotated bibliography can be part of a larger research project or it can be a stand-alone report in itself.

Types of Annotations

 A summary annotation describes the source by answering the following questions: who wrote the document, what the document discusses, when and where was the document written, why was the document produced, and how was it provided to the public. The focus is on description. 

 An evaluative annotation includes a summary as listed above but also critically assesses the work for accuracy, relevance, and quality. Evaluative annotations can help you learn about your topic, develop a thesis statement, decide if a specific source will be useful for your assignment, and determine if there is enough valid information available to complete your project. Each entry might also include: the disciplinary or professional context of the source; the probable audience the source is aimed at; a brief evaluation of the source; or a reflection of how the source fits in with your research. The focus is on description and evaluation.

Writing an Evaluative Annotation

• Cite the source using APAstyle.
• Describe the main ideas, arguments, themes, theses, or methodology, and identify the intended audience.
• Explain the author’s expertise, point of view, and any bias they might have.
• Compare to other sources on the same topic that you have also cited to show similarities and differences.
• Explain why each source is useful for your research topic and how it relates to your topic.
• Evaluate the strengths and weaknesses of each source.
• Identify the observations or conclusions of the author. 

Sample Evaluative Annotation

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APA Citation Guide (7th edition) : Annotated Bibliography

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Useful Links for Annotated Bibliographies

• Writing an Annotated Bibliography Overview and examples from the University of Guelph.
• Writing an Annotated Bibliography Definition, tips, and examples from the University of Toronto.

Example Annotated Bibliography

• Sample Annotated Bibliography

Annotations

An annotated bibliography is a list of citations for various books, articles, and other sources on a topic. The annotated bibliography looks like a Reference page but includes an annotation after each source cited. An annotation is a short summary and/or critical evaluation of a source. Annotated bibliographies can be part of a larger research project, or can be a stand-alone report in itself.

Types of Annotations

 A summary annotation describes the source by answering the following questions: who wrote the document, what the document discusses, when and where was the document written, why was the document produced, and how was it provided to the public. The focus is on description. 

 An evaluative annotation includes a summary as listed above but also critically assesses the work for accuracy, relevance, and quality. Evaluative annotations can help you learn about your topic, develop a thesis statement, decide if a specific source will be useful for your assignment, and determine if there is enough valid information available to complete your project. The focus is on description and evaluation.

How to Write an Evaluative Annotation

Parts of an evaluative annotation:

• Cite the source using APA style.
• Describe the main ideas, arguments, themes, theses, or methodology, and identify the intended audience.
• Explain the author’s expertise, point of view, and any bias he/she may have.
• Compare to other sources on the same topic that you have also cited to show similarities and differences.
• Explain why each source is useful for your research topic and how it relates to your topic.
• Evaluate the strengths and weaknesses of each source.
• Identify the observations or conclusions of the author. 

Below is a sample of an Evaluative Annotation:

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Annotated Bibliography

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• URL: https://libguides.enc.edu/writing_basics/annotatedbib
• Definition and Descriptions
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Research Tools

American Psychological Association (APA) Annotations

Creating an annotated bibliography in APA style

The Publication Manual of the American Psychological Association  7th edition (APA Manual) is kept behind the iDesk on the First Floor.

This example is based on the APA style guide, but your instructor might give you other formatting instructions . 

General guidelines

Some annotations are merely descriptive , summarizing the authors' qualifications, research methods, and arguments. 

Many annotations evaluate the quality of scholarship in a book or article.  You might want to consider the logic of authors' arguments, and the quality of their evidence.  Your findings can be positive, negative, or mixed.

Your professor might also want you to explain why the source is relevant to your assignment. 

Sample Page: APA-formatted annotated bibliography

Rules! rules! rules!

The Publication Manual of the American Psychological Association (7th ed.) states the following formatting rules:

• The text and the reference list should be double-spaced.
• Numbering starts on the title page, at the top right of the page.
• Reference list entries must have a hanging indent (to do this in Microsoft Word 2003, click Format, then Paragraph, then Special, and choose Hanging).
• There should be 1 inch (2.54 cm) margins all around (top, bottom, left, and right) on each page.
• Use Times Roman font, or a similar serif font.
• Each paragraph should be indented.

More Sample Annotations

Cornell University Library offers these instructions on preparing an annotated bibliography.

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Creating an Annotated Bibliography in APA Style

Definitions.

A bibliography is a list of source material, cited in whatever citation style you're required to use in a specific course.

An annotation is a summary and/or evaluation.

Put the two together and you have an Annotated Bibliography !

An annotated bibliography is an organizational tool . an annotated bibliography....

• Is an alphabetical list of all of your source material
• Includes sources you may or may not use in your research
• Summarizes each resource so you can remember what it's about
• Can include any type of resource unless specified in the assignment instructions (For an overview of the types of resources you can find through our library, view our description of resource types on our Evaluating Sources guide .)

Why must you do an Annotated Bibliography?

• If you're utilizing print resources through the library, you may not be able to renew items. How will you remember what the resource was about if you have to send it back?
• If you're utilizing electronic resources, nothing online is permanent. How will you find the resource again if it disappears?
• In larger projects, every resource starts to look the same. An Annotated Bibliography can save you time by reminding you of what you've already found.

What types of resources are used?

An Annotated Bibliography can include any type of resource unless otherwise specified by the assignment. This can include (but is not limited to):

• Scholarly materials
• Government documents

Annotated Bibliographies can be a great resource for students before they write other types of assignments, like literature reviews . 

There are TWO PARTS to each entry in an Annotated Bibliography. They are:

• The citation of the resource , in whatever citation style you're required to use.
• The annotation describing the contents of the resource and how it may or may not contribute to your research.

Be sure to carefully read over the assignment instructions when you're asked to compose an Annotated Bibliography, and reach out to your professor with any questions!

Citation Help

Consult your course style guide to confirm the accuracy of your citation. 

You can also...

• View our guide for  APA Style Help .
• Consult resources like Academic Writer  or  Grammarly .

Skimming Sources

Focus on key areas of a text to learn enough so that you can write a strong annotation. This includes:

• Abstracts, prefaces, and summaries
• Paragraph headings
• Charts/graphs/images and their captions
• Introduction paragraph(s)
• Conclusion paragraph(s)
• Sources/References/Bibliography

These areas will provide you with enough information to determine the topic, arguments, and conclusions drawn from any research presented.

Writing Annotations

A strong annotation will have three main parts:

Length requirements can vary from a few sentences to a single paragraph or a full page. Be sure to verify length requirements with your professor and/or through the assignment instructions.

When writing the summary, ask yourself:

• What topics are covered in the resource?
• What are the main arguments?
• What are the main conclusions drawn from the resource?

When writing the assessment, ask yourself:

• Is the source useful?
• How does it compare to your other resources?
• Is there bias present?
• Is the source reliable?

Our guide for Evaluating Your Sources can help you assess your research material.

When writing the reflection, ask yourself:

• How does the source fit into your research?
• How might the source support your argument?
• Did the source change your mind about the topic?

Sample APA Style citation with annotation:

Bell, C., & Holder, M. (2019, January/February). The Interrelationship between Race, Social Norms, and Dietary Behaviors among College-attending

Women. American Journal of Health Behavior , 43 (1), 23-36.

This article examines a study conducted to compare racial identity and dietary habits of women on college campuses. The findings of the

study found that women with perceived differences and social/family norms were more likely to develop unhealthy dietary habits in college,

most specifically related to fruit and vegetable consumption. This resource is useful because it examines self-perception of race and how that

can impact behavior in ways that influence one's health in the future.

View a full example in APA Style:

• Annotated Bibliography Example- APA Style A full Annotated Bibliography formatted in APA Style. Users, please verify that formatting matches your course style guide's requirements.
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APA Citation Guide (7th edition) : Sample Paper, Reference List & Annotated Bibliography

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• APA Sample Paper Template

This sample paper includes a title page, sample assignment page and references list in APA format. It can be used as a template to set up your assignment.

Sample Paper With Comments and Explanations

The American Psychological Association (APA) has created a sample paper that includes explanations of the elements and formatting in APA 7th ed. 

If your instructor requires you to use APA style headings and sub-headings, this document will show you how they work.

• APA Headings This sample demonstrates and describes how to use different levels of headings in APA format.

If you are adding an appendix to your paper there are a few rules to follow that comply with APA guidelines:

• The Appendix appears  after  the References list
• If you have more than one appendix you would name the first appendix Appendix A, the second Appendix B, etc.
• The appendices should appear in the order that the information is mentioned in your essay
• Each appendix begins on a new page
• APA Sample Paper Template - with Appendix

APA End of Paper Checklist

• End of Paper Checklist

Finished your assignment? Use this checklist to be sure you haven't missed any information needed for APA style.

Quick Rules for an APA Reference List

Your research paper ends with a list of all the sources cited in the text of the paper. Here are nine quick rules for this Reference list.

• Start a new page for your Reference list. Centre the title, References, at the top of the page.
• Double-space the list.
• Start the first line of each reference at the left margin; indent each subsequent line five spaces (a hanging indent).
• Put your list in alphabetical order. Alphabetize the list by the first word in the reference. In most cases, the first word will be the author’s last name. Where the author is unknown, alphabetize by the first word in the title, ignoring the words a, an, the.
• For each author, give the last name followed by a comma and the first (and middle, if listed) initials followed by periods.
• Italicize the titles of these works: books, audiovisual material, internet documents and newspapers, and the title and volume number of journals and magazines.
• Do not italicize titles of most parts of works, such as: articles from newspapers, magazines, or journals / essays, poems, short stories or chapter titles from a book / chapters or sections of an Internet document.
• In titles of non-periodicals (books, videotapes, websites, reports, poems, essays, chapters, etc), capitalize only the first letter of the first word of a title and subtitle, and all proper nouns (names of people, places, organizations, nationalities).
• If a web source (not from the library) is not a stable archived version, or you are unsure whether it is stable, include a statement of the accessed date before the link.

What is an Annotated Bibliography?

An annotated bibliography is a list of citations for various books, articles, and other sources on a topic. The annotated bibliography looks like a Reference page but includes an annotation after each source cited. An annotation is a short summary and/or critical evaluation of a source. Annotated bibliographies can be part of a larger research project, or can be a stand-alone report in itself.

Types of Annotations

 A summary annotation describes the source by answering the following questions: who wrote the document, what the document discusses, when and where was the document written, why was the document produced, and how was it provided to the public. The focus is on description. 

 An evaluative annotation includes a summary as listed above but also critically assesses the work for accuracy, relevance, and quality. Evaluative annotations can help you learn about your topic, develop a thesis statement, decide if a specific source will be useful for your assignment, and determine if there is enough valid information available to complete your project. The focus is on description and evaluation.

Annotated Bibliographies: How-To Guide

• APA Annotated Bibliography Template

Below is a sample of an Evaluative Annotation:

• Annotated Bibliographies Overview of purpose and form of annotated bibliographies from the Purdue OWL.
• Writing an Annotated Bibliography Overview and examples from the University of Guelph.
• Writing an Annotated Bibliography Definition, tips, and examples from the University of Toronto.
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Writing annotations.

• Introduction
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• Sample Annotated Bibliographies

An annotation is a brief note following each citation listed on an annotated bibliography.  The goal is to briefly summarize the source and/or explain why it is important for a topic.  They are typically a single concise paragraph, but might be longer if you are summarizing and evaluating.

Annotations can be written in a variety of different ways and it’s important to consider the style you are going to use.  Are you simply summarizing the sources, or evaluating them?  How does the source influence your understanding of the topic?  You can follow any style you want if you are writing for your own personal research process, but consult with your professor if this is an assignment for a class.

Annotation Styles

• Combined Informative/Evaluative Style - This style is recommended by the library as it combines all the styles to provide a more complete view of a source.  The annotation should explain the value of the source for the overall research topic by providing a summary combined with an analysis of the source.  

Aluedse, O. (2006). Bullying in schools: A form of child abuse in schools.  Educational Research Quarterly ,  30 (1), 37.

The author classifies bullying in schools as a “form of child abuse,” and goes well beyond the notion that schoolyard bullying is “just child’s play.” The article provides an in-depth definition of bullying, and explores the likelihood that school-aged bullies may also experience difficult lives as adults. The author discusses the modern prevalence of bullying in school systems, the effects of bullying, intervention strategies, and provides an extensive list of resources and references.

Statistics included provide an alarming realization that bullying is prevalent not only in the United States, but also worldwide. According to the author, “American schools harbor approximately 2.1 million bullies and 2.7 million victims.” The author references the National Association of School Psychologists and quotes, “Thus, one in seven children is a bully or a target of bullying.” A major point of emphasis centers around what has always been considered a “normal part of growing up” versus the levels of actual abuse reached in today’s society.

The author concludes with a section that addresses intervention strategies for school administrators, teachers, counselors, and school staff. The concept of school staff helping build students’ “social competence” is showcased as a prevalent means of preventing and reducing this growing social menace. Overall, the article is worthwhile for anyone interested in the subject matter, and provides a wealth of resources for researching this topic of growing concern.

(Renfrow & Teuton, 2008)

• Informative Style -  Similar to an abstract, this style focuses on the summarizing the source.  The annotation should identify the hypothesis, results, and conclusions presented by the source.

Plester, B., Wood, C, & Bell, V. (2008). Txt msg n school literacy: Does texting and knowledge of text abbreviations adversely affect children's literacy attainment? Literacy , 42(3), 137-144.

Reports on two studies that investigated the relationship between children's texting behavior, their knowledge of text abbreviations, and their school attainment in written language skills. In Study One, 11 to 12 year-old children reported their texting behavior and translated a standard English sentence into a text message and vice versa. In Study Two, children's performance on writing measures were examined more specifically, spelling proficiency was also assessed, and KS2 Writing scores were obtained. Positive correlations between spelling ability and performance on the translation exercise were found, and group-based comparisons based on the children's writing scores also showed that good writing attainment was associated with greater use of texting abbreviations (textisms), although the direction of this association is not clear. Overall, these findings suggest that children's knowledge of textisms is not associated with poor written language outcomes for children in this age range. 

(Beach et al., 2009)

• Evaluative Style - This style analyzes and critically evaluates the source.  The annotation should comment on the source's the strengths, weaknesses, and how it relates to the overall research topic.

Amott, T. (1993). Caught in the Crisis: Women in the U.S. Economy Today . New York: Monthly Review Press.

A very readable (140 pp) economic analysis and information book which I am currently considering as a required collateral assignment in Economics 201. Among its many strengths is a lucid connection of "The Crisis at Home" with the broader, macroeconomic crisis of the U.S. working class (which various other authors have described as the shrinking middle class or the crisis of de-industrialization).

(Papadantonakis, 1996)

• Indicative Style - This style of annotation identifies the main theme and lists the significant topics included in the source.  Usually no specific details are given beyond the topic list . 

Example: 

Gambell, T.J., & Hunter, D. M. (1999). Rethinking gender differences in literacy. Canadian Journal of Education , 24(1) 1-16.

Five explanations are offered for recently assessed gender differences in the literacy achievement of male and female students in Canada and other countries. The explanations revolve around evaluative bias, home socialization, role and societal expectations, male psychology, and equity policy.

(Kerka & Imel, 2004)

Beach, R., Bigelow, M., Dillon, D., Dockter, J., Galda, L., Helman, L., . . . Janssen, T. (2009). Annotated Bibliography of Research in the Teaching of English.  Research in the Teaching of English,   44 (2), 210-241. Retrieved from http://www.jstor.org/stable/27784357

Kerka, S., & Imel, S. (2004). Annotated bibliography: Women and literacy.  Women's Studies Quarterly,  32 (1), 258-271. Retrieved from http://search.proquest.com/docview/233645656?accountid=2909

Papadantonakis, K. (1996). Selected Annotated Bibliography for Economists and Other Social Scientists.  Women's Studies Quarterly,   24 (3/4), 233-238. Retrieved from http://www.jstor.org/stable/40004384

Renfrow, T.G., & Teuton, L.M. (2008). Schoolyard bullying: Peer victimization an annotated bibliography. Community & Junior College Libraries, 14(4), 251-­275. doi:10.1080/02763910802336407

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Computer Science > Sound

Title: realman: a real-recorded and annotated microphone array dataset for dynamic speech enhancement and localization.

Abstract: The training of deep learning-based multichannel speech enhancement and source localization systems relies heavily on the simulation of room impulse response and multichannel diffuse noise, due to the lack of large-scale real-recorded datasets. However, the acoustic mismatch between simulated and real-world data could degrade the model performance when applying in real-world scenarios. To bridge this simulation-to-real gap, this paper presents a new relatively large-scale Real-recorded and annotated Microphone Array speech&Noise (RealMAN) dataset. The proposed dataset is valuable in two aspects: 1) benchmarking speech enhancement and localization algorithms in real scenarios; 2) offering a substantial amount of real-world training data for potentially improving the performance of real-world applications. Specifically, a 32-channel array with high-fidelity microphones is used for recording. A loudspeaker is used for playing source speech signals. A total of 83-hour speech signals (48 hours for static speaker and 35 hours for moving speaker) are recorded in 32 different scenes, and 144 hours of background noise are recorded in 31 different scenes. Both speech and noise recording scenes cover various common indoor, outdoor, semi-outdoor and transportation environments, which enables the training of general-purpose speech enhancement and source localization networks. To obtain the task-specific annotations, the azimuth angle of the loudspeaker is annotated with an omni-direction fisheye camera by automatically detecting the loudspeaker. The direct-path signal is set as the target clean speech for speech enhancement, which is obtained by filtering the source speech signal with an estimated direct-path propagation filter.

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• Published: 01 July 2024

Improving the accuracy of genomic prediction in dairy cattle using the biologically annotated neural networks framework

• Xue Wang 1 ,
• Shaolei Shi 1 ,
• Md. Yousuf Ali Khan 1 , 2 ,
• Zhe Zhang   ORCID: orcid.org/0000-0001-7338-7718 3 &
• Yi Zhang   ORCID: orcid.org/0000-0003-1642-5890 1  

Journal of Animal Science and Biotechnology volume  15 , Article number:  87 ( 2024 ) Cite this article

Metrics details

Biologically annotated neural networks (BANNs) are feedforward Bayesian neural network models that utilize partially connected architectures based on SNP-set annotations. As an interpretable neural network, BANNs model SNP and SNP-set effects in their input and hidden layers, respectively. Furthermore, the weights and connections of the network are regarded as random variables with prior distributions reflecting the manifestation of genetic effects at various genomic scales. However, its application in genomic prediction has yet to be explored.

This study extended the BANNs framework to the area of genomic selection and explored the optimal SNP-set partitioning strategies by using dairy cattle datasets. The SNP-sets were partitioned based on two strategies–gene annotations and 100 kb windows, denoted as BANN_gene and BANN_100kb, respectively. The BANNs model was compared with GBLUP, random forest (RF), BayesB and BayesCπ through five replicates of five-fold cross-validation using genotypic and phenotypic data on milk production traits, type traits, and one health trait of 6,558, 6,210 and 5,962 Chinese Holsteins, respectively. Results showed that the BANNs framework achieves higher genomic prediction accuracy compared to GBLUP, RF and Bayesian methods. Specifically, the BANN_100kb demonstrated superior accuracy and the BANN_gene exhibited generally suboptimal accuracy compared to GBLUP, RF, BayesB and BayesCπ across all traits. The average accuracy improvements of BANN_100kb over GBLUP, RF, BayesB and BayesCπ were 4.86%, 3.95%, 3.84% and 1.92%, and the accuracy of BANN_gene was improved by 3.75%, 2.86%, 2.73% and 0.85% compared to GBLUP, RF, BayesB and BayesCπ, respectively across all seven traits. Meanwhile, both BANN_100kb and BANN_gene yielded lower overall mean square error values than GBLUP, RF and Bayesian methods.

Our findings demonstrated that the BANNs framework performed better than traditional genomic prediction methods in our tested scenarios, and might serve as a promising alternative approach for genomic prediction in dairy cattle.

Genomic selection [ 1 ] has significantly shortened the generation interval and increased the annual genetic gain of economic traits in dairy cattle [ 2 , 3 , 4 ] with breeding costs reduced by 92% compared to traditional progeny testing [ 5 ]. Statistical models serve as one of the key factors affecting the accuracy of genomic selection, consequently exerting an impact on genetic progress. Currently, the most commonly used models for genomic prediction in dairy cattle include the best linear unbiased prediction (BLUP) models that incorporate genomic information [e.g., the genomic BLUP (GBLUP) and single-step GBLUP (ssGBLUP) methods], executed through solving the mixed model equations (MME), as well as the Bayesian methods with various priors that use Markov chain Monte Carlo (MCMC) to estimate the required genetic parameters. However, the utilization of these linear models is often limited by their assumption that genetic variants influence phenotypes only in an additive manner and fail to capture interactions. The exponential growth of large-scale genomic databases provides a unique opportunity to move beyond traditional linear regression frameworks.

Machine learning (ML) algorithms can build complex nonlinear models and allow interaction between features (i.e., markers). Therefore, ML has been considered an effective tool for interpretating massive genomic datasets [ 6 ]. Recently, several studies showed that nonlinear ML algorithms typically exhibited higher predictive accuracy than conventional methods such as GBLUP and Bayesian approaches [ 6 , 7 , 8 , 9 ], especially for complex traits with broad-sense heritability driven by non-additive genetic variation (e.g., gene-gene interactions) [ 10 ]. In dairy science, ML has been successfully applied to predict a whole range of different traits, such as milk production [ 11 , 12 ], mastitis [ 13 ], and methane production [ 14 ]. Ensemble methods are a category of advanced ML algorithms. Random forest (RF), as an ensemble method, is model specification free and may account for non-additive effects [ 15 ]. Moreover, it remains a relatively fast algorithm in ensemble methods even when dealing with a large number of covariates and interactions, making it suitable for both classification and regression problems [ 15 ]. Therefore, RF has been widely employed in genomic prediction [ 9 , 15 , 16 ]. Furthermore, to comprehensively capture interactions between markers and non-additive effects, an increasing body of research is being devoted to neural networks [ 17 , 18 , 19 ], which reflect the nonlinear relationships between variables by exploiting nonlinear activation functions between network layers. However, conventional neural networks often do not consider the varying influences of different genomic regions on traits, and thus lack certain biological interpretability. Studies have shown that genetic variants do not contribute equally to genetic variance, and genetic variations of large effect on a trait are often distributed within specific genomic regions [ 20 , 21 , 22 ]. Based on this framework, new prediction methods have been developed, including BayesRC [ 23 ], BayesRS [ 24 ], BayesRR-RC [ 25 ], NN-Bayes and NN-MM [ 26 ].

Most recently, Demetci et al. [ 27 ] developed the biologically annotated neural networks (BANNs), a nonlinear probabilistic framework for association mapping in genome-wide association studies (GWAS). BANNs are a class of feedforward Bayesian models that integrate predefined SNP-set annotations, and the BANNs framework has achieved better performance than state-of-the-art methods in the area of GWAS by using prior defined biology information [ 27 ]. BANNs employ variational inference for parameter estimation, which is an optimization method that can leverage modern optimization techniques such as Stochastic Gradient Descent (SGD), to find an approximation to the posterior distribution. Consequently, variational inference is often more efficient than MCMC sampling, as the latter requires extensive sampling to estimate the full posterior distribution [ 28 ]. Philosophically, compared to traditional linear models, the BANNs framework considers the heterogeneity of the function of SNP-sets according to annotations. BANNs take into account the interactions between markers through setting of neural network layers, which seems theoretically more in line with the biological process of complex traits. However, the existing BANNs framework has not been applied to genomic prediction.

The objectives of this study were to: (i) extend the BANNs framework to the field of dairy cattle genomic selection by exploring the optimal SNP-set partitioning strategies; and (ii) assess the predictive ability of the BANNs framework by comparing it with GBLUP, RF and Bayesian methods.

Materials and methods

Statistical models.

As an interpretable neural network, the BANNs framework models SNP effects in the input layers and SNP-set effects in the hidden layers separately. BANNs utilized sparse prior distributions to select variables for network weights. The weights and connections of the network are treated as random variables that present genetic effects at various genomic scales. Moreover, BANNs fall into the category of Bayesian Network (BN) models. BN models can be viewed as a non-conjugate form of Bayesian linear regression, because they automatically learn hyperparameters for priors from the data, making them generally more flexible and better suitable for capturing complex data structures [ 29 ].

The model representation for the BANNs framework is as follows:

where \(\varvec{y}\) is the vector of the response variable, that is, standardized de-regressed proofs (DRPs); \({\varvec{X}}_{g}=\left[{\varvec{x}}_{1},\dots ,{\varvec{x}}_{\left|{S}_{g}\right|}\right]\) is a subset of SNPs for SNP-set \(g\) ; \({\varvec{\theta }}_{g}=\left({\theta }_{1},\dots ,{\theta }_{\left|{S}_{g}\right|}\right)\) are the corresponding inner layer weights; \(h\left(\bullet \right)\) denotes the nonlinear activations defined for the neurons in the hidden layer; \({\varvec w}=\left({w}_{1},\cdots ,{w}_{G}\right)\) are the weights of the G-predefined SNP-sets in the hidden layer; \({\varvec{b}}^{\left(1\right)}=\left({b}_{1}^{\left(1\right)},\cdots ,{b}_{G}^{\left(1\right)}\right)\) and \({b}^{\left(2\right)}\) are deterministic biases generated during the training phase of the network in the input and hidden layers, respectively; 1 is an N-dimensional vector of ones. For convenience, the genotype matrix (column-wise) and the trait of interest are assumed to be mean-centered and standardized. In this study, \(h\left(\bullet \right)\) is defined as the Leaky rectified linear unit (Leaky ReLU) activation function. If x  > 0, then \(h\left(x\right)=x\) , otherwise, we define \(h\left(x\right)=0.01x\) .

The weights of the input layer ( \(\varvec{\theta }\) ) and the hidden layer ( \({\varvec w}\) ) were treated as random variables, allowing simultaneous multi-scale genomic inference on both SNPs and SNP-sets. SNP-level effects are assumed to follow a sparse K-mixed normal distribution:

where \({\pi }_{\theta }\) represents the total proportion of SNPs that have a non-zero effect on the trait; \({\varvec{\eta }}_{\theta }=\left({\eta }_{\theta 1},\dots ,{\eta }_{\theta k}\right)\) denotes the marginal (unconditional) probability that a randomly selected SNP belongs to the k-th mixture component and that \({\sum }_{k}{\eta }_{\theta \kappa }\) =1; \({\varvec{\sigma }}_{\theta }^{2}=\left({\sigma }_{\theta 1}^{2},\dots ,{\sigma }_{\theta K}^{2}\right)\) are the variance of the K non-zero mixture components; and \({\delta }_{0}\) is a point mass at the zero point. The present study follows previous studies and lets K = 3, indicating that SNPs may have large, moderate and small non-zero effects on phenotypic variation [ 30 , 31 , 32 ]. To infer the hidden layer, it was assumed that the enriched SNP-sets contain at least one non-zero effect SNP by placing a spike and slab prior to the hidden weights:

Due to the lack of prior knowledge regarding the proportion of relevant SNPs and SNP-sets with non-zero weights, an assumption was made on relatively uniform priors on \(\text{log}\left({\pi }_{\theta }\right)\) and \(\text{log}\left({\pi }_{w}\right)\) [ 27 ]:

where \({\pi }_{\theta }\) denotes the total proportion of SNPs with a non-zero effect on the trait of interest, \(J\) denotes the number of SNPs, and \({\pi }_{w}\) denotes the total proportion of annotated SNP-sets enriched for the trait of interest. In addition, the variational Bayesian algorithm was used to estimate all model parameters. In the BANNs framework, the posterior inclusion probabilities (PIPs) provide statistical evidence for the importance of each variant in explaining the overall genetic architecture of a trait. These quantities are defined as the posterior probability that the weight of a given connection in the neural network is non-zero:

where \(j\) and \(g\) represent a specific SNP and a specific SNP-set, respectively.

In addition, the variational expectation-maximization (EM) algorithm was utilized for estimating the parameters of the neural network, and parameters in the variational EM algorithm were initialized through random draws from their assumed prior distributions. The iteration within the algorithm terminates upon meeting one of the following two stopping criteria: (i) the difference between the lower bounds of two consecutive updates falls within the range of 1 × 10 −4 , or (ii) the maximum iteration count of 10,000 is reached [ 27 ]. In addition, the initial values of variance \({\sigma }_{0}^{2}\) and the number of models L were set to 0.01 and 20, respectively. In summary, the Bayesian formulation in the BANNs framework makes network sparsity a goal for genomic selection applications through the context-driven sparse shrinkage prior distribution in Eqs. ( 1 – 4 ).

The original BANNs model partitioned SNP-sets according to gene-annotated SNPs. Two strategies were considered in this study to group the SNPs into different sets. Firstly, biological annotations were considered (denoted as BANN_gene). The cattle genome annotation file was obtained from the NCBI website ( https://ftp.ensembl.org/pub/release-94/gtf/bos_taurus/ ) for mapping SNPs to their nearest neighboring genes and aptly annotating them with relevant gene information. Unannotated SNPs located within the same genomic region were denoted as “intergenic regions” between two genes. A total of G = 16,857 SNP-sets were analyzed, consisting of 9,369 intergenic SNP-sets and 7,488 annotated genes. Secondly, 100 kb windows were used to divide SNPs on each chromosome into different groups (denoted as BANN_100kb). A total of G = 22,626 SNP-sets were analyzed using this strategy. On note, the choice of a 100 kb window was based on our testing of the predictive ability with different SNP division intervals (50 kb, 100 kb, 200 kb, 300 kb, 400 kb, 600 kb, 800 kb, 1,000 kb), where we found that dividing based on a 100 kb window yielded better results (results not shown).

The model of the GBLUP is given as:

in which \({\varvec y}\) is also the vector of standardized DRPs, \(\mu\) is the overall mean, \({\boldsymbol 1}\) is a vector of ones, \({\varvec g}\) is the vector of genomic breeding values, \({\varvec e}\) is the vector of random residuals, and Z is an incidence matrix allocating records to \(\varvec g\) . The assumptions of random effects were:

in which G is the genomic relationship matrix ( G matrix), D is a diagonal matrix with \({d}_{ii}=\frac{1-{r}_{i}^{2}}{{r}_{i}^{2}}\) , ( \({r}_{i}^{2}\) is the reliability of DRP of individual i ), and \({\sigma }_{{g}}^{2}\) and \({\sigma }_{{e}}^{2}\) are the additive genetic variance and the random residual variance, respectively.

In this study, GBLUP was carried out using DMU software [ 33 ]. The AI-REML method in the DMUAI procedure was used to estimate the variance components.

In BayesB, the proportion of markers with no effect is assumed to be \(\pi\) , and the proportion of markers with an effect is \(1-\pi\) , and the prior distribution of SNP effect, \({\beta }_{k}\) , was assumed to be t -distributed. The formula of BayesB can be written as follows:

where \(\varvec y\) represents the vector of standardized DRPs, \({\varvec{x}}_{\varvec{k}}\) is the vector of genotypes for the k th SNP, and \({\beta }_{k}\) is the effect of the k th SNP. The prior distribution of \({\beta }_{k}\) is as follows:

in which \(v\) is the degree of freedom, \({S}_{\beta }^{2}\) is the scale parameter. In the present study, for the BayesB method, we set the proportion of no-effect SNPs ( \(\pi\) ) to be 0.95.

In BayesCπ, the marker effects are sampled from a mixture of null and normal distributions. The expression for BayesCπ aligns with that of BayesB except for the prior distribution of \({\upbeta }_{k}\) , which is as follows:

where \({\sigma }_{\beta}^{2}\) is the variance of SNP effect. Additionally, in BayesCπ, the value of \(\pi\) is treated as an unknown with uniform (0,1) prior and is estimated through sampling [ 34 ].

For both BayesB and BayesCπ methods, the MCMC chain was run for 50,000 iterations, the first 20,000 iterations were discarded as burn-in, and every 50 samples of the remaining 30,000 iterations were saved to estimate SNP effects and variance components. The analysis was performed using the Julia package JWAS [ 35 ].

Random forest

Random forest is a ML algorithm that employs voting or averaging the outcomes of multiple decision trees to determine the classification or predicted values of new instances [ 36 ]. Essentially, RF is a collection of decision trees, with each tree exhibiting slight differences from the others. RF reduces the risk of overfitting by averaging the predictions of numerous decision trees [ 7 ]. The RF regression can be expressed as follows:

where \({y}\) represents the predicted value from the RF regression, \({t}_{m}\left({\psi }_{m}\left({y}:{\varvec X}\right)\right)\) represents an individual regression tree, and \(M\) represents the number of decision trees in the forest. Predictions were obtained by propagating predictor variables through the flowchart of each tree, with the estimated values at the terminal nodes serving as the predictions. The final predictions for unobserved data were determined by averaging the predictions across all trees in the RF. To optimize the model, a grid search approach was employed to identify the most suitable hyperparameter \(M\) and the maximum tree depth, with an inner five-fold cross-validation (CV) being conducted to tune these hyperparameters.

In this study, phenotypic and genomic data were collected from Chinese Holstein cattle. The population and phenotype information are shown in Table  1 . The phenotypic data included three milk production traits: milk yield (MY), fat yield (FY) and protein yield (PY); three type traits: conformation (CONF), feet and leg (FL) and mammary system (MS); and one health trait: somatic cell score (SCS). A total of 6,558, 6,210 and 5,962 individuals were genotyped for milk production traits, type traits and SCS, respectively. DRPs derived from the official estimated breeding values (EBV) provided by the Dairy Association of China following the method proposed by Jairath et al. [ 37 ] were used as pseudo-phenotypes for genomic predictions. The DRP reliability for each animal was estimated as \({r}_{DRP}^{2}=\frac{{ERC}_{i}}{{ERC}_{i}+\lambda }\) , with \(\lambda =\frac{1-{h}^{2}}{{h}^{2}}\) , in which \({ERC}_{i}\) refers to the effective record contribution and \({h}^{2}\) refers to the heritability of the trait. Note that \({ERC}_{i}=\lambda \times\frac{{REL}_{i}}{1-{REL}_{i}}\) , where \({REL}_{i}\) is the reliability of EBV for individual i . All individuals were genotyped using the BovineSNP50 chip containing 54,609 SNPs from Illumina (Illumina, San Diego, CA, USA). Missing genotypes were imputed using Beagle 5.4 [ 38 ]. After imputation, SNPs with minor allele frequency (MAF) less than 0.01 and significantly deviating from Hardy-Weinberg equilibrium ( P  < 1.0E-6) were removed using PLINK software [ 39 ]. After genotype quality control, 45,944 autosomal SNPs remained for further analyses.

Cross-validation and genomic prediction accuracy

Prediction accuracy, mean square error (MSE) and dispersion were used to assess the prediction performance of different methods. A 5 × 5 CV (five-fold CV repeated five times, totaling 25 tests) process was carried out. The prediction accuracy was assessed with the Pearson correlation coefficient between standardized DRP (sDRP) and predicted values (PV) of the validation population divided by the mean accuracy \(\stackrel{-}{r}\) (square root of reliability) of DRP in validation data:

Besides, following the study by Legarra and Reverter [ 40 ], the slope of the regression of sDRP on PV was calculated to assess the dispersion of the prediction, although some studies used the regression coefficient as a measure of bias and referred to it as unbiasedness [ 30 , 41 ]. In addition, MSE was also used as a measure for the performance of different methods, which considered both prediction bias and variability. In each prediction scenario, the reference and validation populations for all methods were the same in each replicate of the five-fold CV, and the final results of accuracy, dispersion and MSE are the averages of five repetitions. Furthermore, multiple t -tests were conducted based on the outcomes of five replicates, with P -values adjusted using the Bonferroni method, to compare the prediction accuracy of different methods.

Estimating phenotypic variance explained in the BANNs framework

Given that the BANNs framework offers posterior estimates for all weights in neural networks, it also enables the estimation of phenotypic variance explained (PVE). Here, PVE was defined as the total proportion of phenotypic variation explained by sparse genetic effects (both additive and non-additive effects) [ 42 ]. Within the BANNs framework, such estimation can be conducted at both the SNP and SNP-set levels as follows [ 27 ]:

where \(\text{V}\left(\bullet \right)\) denotes the variance function, \({\varvec{\beta }}_{\theta }\) and \({\varvec{\beta }}_{w}\) represent the vectors of the marginal posterior means for the input and outer layer weights, respectively. \(\varvec{H}\left({\varvec{\beta }}_{\theta }\right)=\left[h\left({\varvec{X}}_{1}{\varvec{\beta }}_{\theta 1}+{b}_{1}^{\left(1\right)}\right),\dots , h({\varvec{X}}_{G}{\varvec{\beta }}_{\theta G}+{b}_{G}^{\left(1\right)})\right]\) represents the matrix of deterministic nonlinear neurons in the hidden layer given \({\varvec{\beta }}_{\theta }\) . The estimates of variance hyperparameters \({\tau }_{\theta }^{2}\) and \({\tau }_{w}^{2}\) in the variational EM algorithm were used to approximate the residual variance observed during the two-layer training process [ 27 ]. In fact, the formula is similar to the traditional form used for estimating PVE, with the distinction that the contribution of non-additive genetic effects is also taken into account through the nonlinear Leaky ReLU activation function \(h\left(\bullet \right)\) . In other words, the PVE estimated at the SNP level considers only additive effects, while the PVE estimated at the SNP-set level takes into account both additive and non-additive genetic effects.

Annotation summary

The distribution of the number of SNPs in each SNP-set under the two partitioning schemes is shown in Fig.  1 . With regards to BANN_gene, of a total of 16,857 SNP-sets, 9,413 contained one SNP (including intergenic regions), while the remaining SNP-sets had varying numbers of SNPs, ranging from 2 to 108. For BANN_100kb, among the 22,626 SNP-sets, 21,466 sets had no more than 3 SNPs (7,152, 8,848 and 5,466 SNP-sets containing 1, 2 and 3 SNPs, respectively), and none of the SNP-sets had more than 6 SNPs. Therefore, it was evident that the distribution of SNPs within BANN_100kb SNP-sets was more uniform than in BANN_gene.

The distribution of the number of SNPs included in each SNP-set under two partitioning schemes. a  Partitioning SNP-sets according to gene annotation (BANN_gene). b Partitioning SNP-sets according to 100 kb physical genomic intervals (BANN_100kb)

Genomic prediction accuracy

Comparison of prediction performance among bann_gene, gblup, rf and bayesian methods.

Figure  2 shows the accuracy, dispersion and MSE of genomic predictions for seven dairy cattle traits using six methods (Table S1 reports the underling values of Fig.  2 ). In terms of accuracy, BANN_gene performed best compared to GBLUP, RF and Bayesian methods. The average improvement of BANN_gene over GBLUP, RF, BayesB and BayesCπ were 3.75%, 2.86%, 2.73% and 0.85%, respectively, across all seven traits. For milk production traits, BANN_gene demonstrated better performance compared to GBLUP, RF, BayesB or BayesCπ, especially for MY. For example, the accuracy of BANN_gene for MY was 0.491, which resulted in a 7.68% significant improvement compared to GBLUP. The accuracy of BANN_gene for milk production traits, compared to GBLUP, RF, BayesB and BayesCπ, improved by an average of 3.93%, 3.25%, 1.90% and 1.53%, respectively. In case of type traits, BANN_gene significantly outperformed GBLUP, RF and BayesB, while BayesCπ performed similarly with BANN_gene. The improvement of BANN_gene over GBLUP, RF and BayesB was 3.52%, 2.33% and 3.84% on average, respectively.

Accuracy ( a ), mean squared error (MSE) ( b ) and dispersion ( c ) of genomic prediction on seven traits of dairy cattle using five-fold cross-validation with five replications.  CONF  Conformation, FL  Feet and leg, MS  Mammary system, FY  Fat yield, MY  Milk yield, PY  Protein yield, SCS  Somatic cell score. The error bar represents the standard error

Compared to GBLUP, RF and Bayesian methods, BANN_gene yielded the lowest or the second lowest MSE. It yielded the smallest MSE for FL, FY, MY and SCS traits, while for other traits, BANN_gene showed the second smallest MSE. However, in terms of overall dispersion, BayesCπ achieved the most appropriate dispersion (i.e., slopes closer to 1), followed by BANN_gene.

In addition, for the comparison of the two Bayesian methods, we found that BayesCπ obtained better results than BayesB across all metrics of accuracy, dispersion, and MSE; besides, as indicated by the estimated standard errors of marker effects (as shown in Table  2 ), BayesCπ produced smaller standard errors for marker effects across all traits.

Comparison of prediction performance among BANN_100kb, GBLUP, RF and Bayesian methods

BANN_100kb achieved the highest accuracy in all scenarios when compared to the conventional GBLUP and Bayesian methods, where the accuracy of BANN_100kb was improved by an average of 4.86%, 3.95%, 3.84% and 1.92% compared to GBLUP, RF, BayesB and BayesCπ, ranging from 2.12% to 7.46%, 2.63% to 5.38%, 1.87% to 6.93% and 1.25% to 3.23%, respectively. For milk production traits, BANN_100kb consistently achieved the highest accuracy, particularly for FY and MY traits, where BANN_100kb exhibited significant improvements of 5.42% and 7.46%, respectively, compared to GBLUP. Compared to GBLUP, BayesB and BayesCπ, BANN_100kb displayed average improvements in accuracy of 4.48%, 2.45% and 2.08%, respectively. For type traits, BANN_100kb also obtained the highest accuracy, with average improvements over GBLUP, RF, BayesB and BayesCπ of 5.36%, 4.14%, 5.68% and 1.71%, respectively. These results suggest that BANN_100kb captured some intrinsic nonlinear features within the dairy cattle data, whereas GBLUP and Bayesian methods did not. Regarding MSE, BANN_100kb showed the lowest value for all traits. As for dispersion, the dispersions of the four methods were roughly as follows: b BayesCπ < b BANN_100kb < b GBLUP < b BayesB < b RF .

Comparison of prediction performance between BANN_gene and BANN_100kb

Comparison of the BANNs methods used for differently partitioned SNP subsets (BANN_gene vs. BANN_100kb) showed that BANN_100kb consistently demonstrated superior accuracy with an average improvement of 1.80%, 1.79%, 1.73% and 1.82% over BANN_gene for CONF, FL, MS and FY traits, respectively. However, for MY and SCS traits, the accuracy of BANN_100kb closely resembled that of BANN_gene, with accuracies of 0.49 and 0.491 for MY and 0.351 and 0.352 for SCS. Overall, BANN_100kb resulted in an average improvement of 1.07% compared to BANN_gene across all traits (1.77% for type traits; 0.54% for milk production traits), although the improvements were not significant for most traits.

Concerning MSE, BANN_100kb consistently produced lower MSE than BANN_gene in almost all scenarios. Specially, BANN_100kb had an average MSE that was 0.007 lower than that of BANN_gene for milk production traits and an average MSE that was lower than BANN_gene by 0.0013 for type traits. In terms of dispersion, BANN_100kb achieved a generally more appropriate dispersion compared to BANN_gene for both milk production and type traits.

Posterior inclusion probabilities in the BANNs framework

Table  3 summarizes the average, maximum and minimum values of PIPs across all variants on SNPs and SNP-sets from the BANNs framework. Since BANN_gene and BANN_100kb shared the same SNP layer, both methods yielded identical PIP results at the SNP level. However, at the SNP-set level, BANN_100kb obtained a lower standard error in PIP across all seven traits compared to BANN_gene, as evidenced by the smaller range between the maximum and minimum PIP values obtained by BANN_100kb. In addition, for both BANN_gene and BANN_100kb methods, the maximum PIP values obtained at the SNP-set level were significantly higher than those at the SNP level for all traits.

Figure  3 presents the average PVE for the seven traits in five replicates of five-fold CV. For all traits, the PVE estimates obtained at the SNP-set level were substantially greater than those at the SNP level, regardless of whether they were derived from BANN_gene or BANN_100kb. In addition, as BANN_gene and BANN_100kb shared the same SNP layer, they yielded identical PVE estimates at the SNP level, while at the SNP-set level, BANN_100kb obtained larger PVE estimates. The average PVE estimated at the SNP level for both BANN_gene and BANN_100kb was 0.303, while the average PVE estimated at the SNP-set level was 0.738 and 0.754 respectively. Moreover, we observed that at the SNP-set level, the PVE for type traits (i.e., CONF, FL and MS) was generally greater than that for milk production traits (i.e., MY, FY, PY and SCS). For example, BANN_gene and BANN_100kb had average PVEs of 0.732 and 0.746 respectively for milk production traits, while for type traits, their average PVEs were 0.746 and 0.764, respectively. This might partly explain why type traits achieved higher accuracy compared to milk production traits.

Phenotypic variation explained (PVE) for the seven traits as assessed with five replicates of five-fold CV.  a PVE estimated using the BANNs_gene method. b PVE estimated using the BANNs_100kb method. The error bar represents the standard error

Computation time

The average computation time to complete each fold of five-fold CV for all genomic prediction methods is shown in Table S 2 . The running time of the methods was measured in minutes on an HP server (CentOS Linux 7.9.2009, 2.5 GHz Intel Xeon processor and 515 GB total memory). Among all methods, GBLUP was the fastest algorithm across all traits, with each fold of CV taking an average of 41.76 min to complete the analysis. The computational efficiency of BayesB, with an average of 132.08 min, was comparable to that of BayesCπ, which averaged 148.91 min. As the BANNs framework involves the construction of neural networks, the computation time for BANN_gene (average 275.79 min) and BANN_100kb (average 284.49 min) was longer, roughly twice that of BayesB or BayesCπ. Additionally, we found that the computational efficiency of RF (average 274.10 min) to be close to that of BANN_gene and BANN_100kb. This may be due to RF being an ensemble algorithm, involving the construction of several hundred decision trees, along with data sampling and feature selection for each tree, leading to its computationally intensive process.

The BANNs framework was extended and applied to genomic prediction of dairy cattle for the first time in this study. In addition, two SNP-set partitioning strategies (based on gene annotations and 100 kb windows) under the BANNs framework were also explored. The superiority of the BANNs methodology was demonstrated by using dairy cattle datasets and comparing them to GBLUP, RF and Bayesian methods (BayesB, BayesCπ). BANN_100kb, which partitioned SNP-sets based on 100 kb intervals, outperformed GBLUP, RF, BayesB and BayesCπ methods in terms of prediction accuracy and MSE across all investigated scenarios.

Non-additive effects often play an important role in the phenotypic variation of complex traits [ 43 ]. This is also evident from the PVE results in this study, where the PVE at the SNP-set level, considering both additive and non-additive genetic effects, was substantially higher than the PVE at the SNP level, which accounts only for additive effects (Fig.  3 ). By incorporating nonlinear Leaky ReLU activation functions within the hidden layer, BANN_100kb effectively captured interactions among input variables, enabling the BANNs framework to model sparse genetic effects that encompass both additive and non-additive effects. In contrast, GBLUP and Bayesian methods focus on additive genetics, overlooking potential complex nonlinear relationships between markers and phenotypes (e.g., dominance, epistasis, genotype by environment interactions) [ 9 ]. Additionally, in the BANNs approach, the bias term \({b}_{g}^{\left(1\right)}\) for SNP-sets enables each node in the hidden layer to alter the slope for different genotypic combinations, offering a more flexible estimation of generalized heritability. Theoretically, as more nodes and hidden layers are added to the network architecture, BANNs models will possess an increased capacity to account for non-additive genetic effects, akin to classical Gaussian process regression methods [ 27 ]. Consequently, BANNs may exhibit greater advantages when applied to high density SNP markers or whole-genome sequencing (WGS) data, as the use of WGS data has not improved the accuracy of genomic prediction compared to using high-density SNP panels [ 44 , 45 ]. The BANNs framework could potentially provide a promising direction in this context. This is worth investigating in further studies.

It was found that Bayesian methods generally outperformed GBLUP. Bayesian models’ prediction accuracy is affected by the consistency between the underlying assumptions of the model and the true distribution of marker effects. Bayesian models improved prediction accuracy by shrinking the effects of noisy markers to zero. However, the performance of Bayesian methods over GBLUP mainly depends on the presence of QTLs with large effects on the analyzed trait [ 46 ]. As milk production traits (e.g., FY, MY, PY and SCS) were characterized by major effect QTLs [ 47 ], both BayesB and BayesCπ outperformed the GBLUP method, which assumed all SNP effects follow the same normal distribution. In addition, GWAS on dairy cattle [ 48 ] and beef cattle [ 49 ] have found that only a few SNPs were significant for type traits, suggesting that most genetic variants have similar medium or small effects on the traits. This might be the reason for the similar performance of BayesB and GBLUP in type traits (e.g., CONF, FL and MS). Additionally, it was observed that BayesB yielded more over/under dispersion compared to other methods. Despite BayesCπ producing less over/under dispersion, its prediction accuracy and MSE values across all traits still remained inferior to those of BANN_100kb.

In this study, we observed that the predictive performance of BANN_gene was not as strong as that of BANN_100kb. As shown in Fig.  3 , the PVE values obtained by BANN_100kb at the SNP-set level were greater than that obtained by BANN_gene at the same level for all traits. This indicates a higher proportion of phenotypic variance explained by genetic effects in the BANN_100kb method, which may partially account for its higher accuracy. In addition, as evidenced by the distribution of SNPs (Fig.  1 ), the 100 kb interval partitioning method resulted in a more uniform SNP distribution and formed a larger number of SNP-sets (a total of 22,626 SNP-sets). In contrast, with the gene-based partitioning approach, the distribution of SNPs in the SNP-sets was highly uneven (the number of SNPs in each set ranged from 1 to 108) and many SNP-sets contained only one SNP. In fact, BANNs are likely to rank SNP-set enrichments that are driven by just a single SNP as less reliable than enrichments driven by multiple SNPs with nonzero effects [ 27 ]. Besides, SNP-sets containing only one SNP struggle to capture interactions or combinatorial effects among multiple loci. When the phenotype is affected by multiple variants within a gene region, a SNP-set containing only one SNP may not represent the total genetic contribution of that region, potentially leading to the model overlooking some biological information and thereby affecting its predictive ability. However, retaining these SNPs might still be beneficial compared to removing them, as BANNs are able to prioritize trait relevant SNPs and SNP-sets [ 27 ], and some of these single-SNP sets may contain SNPs that are associated with the traits of interest. In addition, in neural networks, the uneven connectivity between hidden and input layer neurons might also affect the predictive ability of the model, primarily for the following reasons: (I) Uneven connectivity might resulted in an imbalanced weight distribution, causing the network to be unable to capture different aspects of the input data in a balanced manner. This might result in biased feature extraction from the input data, ultimately affecting the model’s generalization ability. (II) Uneven connectivity might lead to unstable gradient updates, resulting in issues such as slow convergence, local optima, gradient explosion, or vanishing gradients during the training process. (III) Due to the uneven connectivity between hidden and input layer neurons, the network might struggle to capture complex relationships and features within the input data. This limitation could have constrained the expressiveness of the network and negatively affected its predictive ability. Consequently, the more uniform distribution of SNPs in BANN_100kb facilitated the network in capturing complex relationships and features within the input data; moreover, the larger number of SNP-sets in BANN_100kb potentially aided the network in extracting more meaningful information. These factors above potentially contributed to the greater advantage of BANN_100kb over BANN_gene. However, when based on high-density SNP panel or WGS data, the number of SNPs within each gene region will significantly increase, enhancing the reliability of SNP-set enrichment rankings [ 27 ]. Therefore, BANN_gene may outperform BANN_100kb under these conditions.

Although BANN_100kb has achieved superior predictive performance in this study, there remain several potential extensions to the BANNs framework. (I) It would be beneficial to explore different prior assumptions and consider alternative (more scalable) approaches for approximate Bayesian inference [ 50 ]. (II) Employing deep learning techniques by incorporating additional hidden layers in the neural network. (III) Consider environmental covariates (as well as potential genotype by environment interactions) in the model [ 27 ]. (IV) Evidence suggested that modeling multiple phenotypes into analytical models often results in a substantial improvement of statistical power [ 51 ]; therefore, extending the BANNs framework to accommodate multiple phenotypes and exploiting phenotype correlations to identify pleiotropic epistatic effects might be beneficial. Moreover, investigating the performance of more SNP partitioning strategies through future experiments would be interesting. For example, (i) LD-based partitioning: since the uneven distribution of LD along the genome (i.e., the LD heterogeneity of LD among regions) has a great impact on genomic prediction [ 52 ], dividing SNP-sets according to LD structure allows SNPs with higher LD to be grouped together, which may improve the ability to explain genetic variation, thus better reflecting the effects of genomic selection; (ii) function-annotation-based partitioning: the genetic variance explained by different functional regions varies across the entire genome [ 53 , 54 ], so dividing SNPs based on gene functional regions could make the resulting SNP-sets more biologically meaningful, such as coding region SNPs, non-coding region SNPs, intronic SNPs, etc. Finally, given that BANNs require more computation time compared to conventional methods (as shown in Table S 2 ), further optimization of the BANNs framework code to reduce computation time remains a worthwhile endeavor.

Conclusions

This study applied the BANNs framework to the field of genomic prediction in dairy cattle, and compared it with GBLUP, RF and Bayesian methods. Our results demonstrated that the BANNs framework holds greater potential for enhancing genomic prediction accuracy than traditional GBLUP, RF and Bayesian methods by modelling interactions between markers, emerging as a novel choice for dairy cattle genomic prediction. Further research might explore the performance of BANNs framework when applied to high density SNP markers and WGS data, together with function-annotation-based partitioning of SNP-sets.

Availability of data and materials

The datasets used or analyzed during the present study are available from the corresponding author on reasonable request.

Abbreviations

• Biologically annotated neural networks

Bayesian network

Conformation

Cross-validation

De-regressed proofs

Estimated breeding values

Expectation-maximization

Feet & leg

Genomic best linear unbiased prediction

Genomic estimated breeding values

Genomic relationship matrix

Linkage disequilibrium

Minor allele frequency

Markov chain Monte Carlo

Machine learning

Mixed model equations

Mammary system

Mean squared error

Posterior inclusion probabilities

Predicted values

Phenotypic variance explained

Protein yield

Somatic cell score

Stochastic gradient descent

Whole-genome sequencing

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Acknowledgements

The authors gratefully acknowledge the constructive comments from reviewers. We thank Professor Stuart Barker (School of Environmental and Rural Science, University of New England) for his English editing to this paper.

This study was supported by the National Key Research and Development Program of China (2022YFD1302204), the earmarked fund CARS36, and Ningxia Key Research and Development Program of China (2023BCF01004; 2019NYYZ09).

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State Key Laboratory of Animal Biotech Breeding, National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China

Xue Wang, Shaolei Shi, Md. Yousuf Ali Khan & Yi Zhang

Bangladesh Livestock Research Institute, Dhaka 1341, Bangladesh

Md. Yousuf Ali Khan

Guangdong Laboratory of Lingnan Modern Agriculture, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China

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Contributions

YZ and ZZ designed and supervised the study. XW wrote the program, analyzed the data, and wrote the manuscript. SLS and MYAK provided help on language polishing. SLS, YZ and ZZ revised the manuscript. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Zhe Zhang or Yi Zhang .

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Ethics approval and consent to participate.

Animal samples used in this study were approved by the Animal Care and Use Committee of China Agricultural University. There was no use of human participants, data or tissues.

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Not applicable.

Competing interests

The authors declare no conflict of interest.

Supplementary Information

Additional file 1: table s1.

Accuracy, dispersion, and mean squared error (MSE) of genomic prediction on seven traits of dairy cattle using five-fold cross-validation with five replications;  Table S2 The average computation time to complete each fold of five-fold CV for all genomic prediction methods.

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Wang, X., Shi, S., Ali Khan, M. et al. Improving the accuracy of genomic prediction in dairy cattle using the biologically annotated neural networks framework. J Animal Sci Biotechnol 15 , 87 (2024). https://doi.org/10.1186/s40104-024-01044-1

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Received : 21 February 2024

Accepted : 05 May 2024

Published : 01 July 2024

DOI : https://doi.org/10.1186/s40104-024-01044-1

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