139 posts categorized "How-to"

November 17, 2011

The Grammar of Mathematics: Percentage or %?

Timothy.mcadooby Timothy McAdoo

As Chelsea so succinctly noted in her recent post about how statistical terms are introduced and used in APA Style manuscripts, “in the social sciences, the worlds of grammar and mathematics intersect.” Thus, when you first start to write about statistical results, you may encounter style questions that you’ve not considered before. In today’s post, I answer one such question:

Question: How do you decide whether to use the percentage symbol (%) or the word percentage?

Answer: Use the symbol only when it is preceded by a numeral; otherwise, spell out the word percentage.

For example,

What percentage of wood would a woodchuck chuck if a woodchuck could chuck wood? In Experiment 1, we used a computer simulation to address this timeless question. The woodchucks (who would chuck) chucked 86.4% of the wood available during the test. This was a larger percentage than we hypothesized. Two woodchucks (33.3% of the virtual subjects) would not chuck wood (see Table 1).

You’ll find these guidelines on page 118 of the Publication Manual. On the same page, the Manual also notes just one exception: "In table headings and figure legends, use the symbol % to conserve space."

Table 1

October 20, 2011

Reference Twins: Or, How to Cite Articles With the Same Authors and Same Year

Chelsea blog 2
by Chelsea Lee

Have you ever been friends with a pair of identical twins? Twins who looked so alike that, at first, telling them apart all hinged on finding that distinguishing freckle, or hoping someone else would call them by their names so you could memorize what clothes each was wearing that day? In the social sciences, there is a longstanding tradition of twin research, but this post refers to twins of another kind: reference twins. Specifically, this post addresses how to cite multiple articles by the same authors that were published in the same year so that everyone can easily tell them apart.

A Solution for Identical Twins

In essence, the solution to the reference twin problem is not much different from how twins are told apart at birth: Just as twins are referred to as “Baby A” and “Baby B,” “twin references” are also given letters to tell them apart. Specifically, lowercase letters are added after the year (2011a, 2011b, etc.), and the references are alphabetized by title to determine which is “a” and which is “b.” Here is an example:

Koriat, A. (2008a). Easy comes, easy goes? The link between learning and remembering and its exploitation in metacognition. Memory & Cognition, 36, 416–428. doi:10.3758/MC.36.2.416
Koriat, A. (2008b). Subjective confidence in one’s answers: The consensuality principle. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 945–959. doi:10.1037/0278-7393.34.4.945

In the text, citations would be styled as follows: (Koriat, 2008a) and (Koriat, 2008b).

For references that are in press or that have no date (signified by n.d., which stands for “no date”), use the following forms for the date: (in press-a), (in press-b), (n.d.-a), and (n.d.-b), and so forth.

A Solution for Not-Quite Twins

However, be careful that your references are true identical twins. That is, the method described above applies only when all author names are the same and appear in the same order. If any of the names or the order is different, then the references are distinguished in a different way: by spelling out as many author names as necessary to tell them apart.  Let’s use the following two references as an example:

Marewski, J. N., Gaissmaier, W., & Gigerenzer, G. (2010). Good judgments do not require complex cognition. Cognitive Processing, 11, 103–121. doi:10.1007/s10339-009-0337-0
Marewski, J. N., Gaissmaier, W., Schooler, L. J., Goldstein, D. G., & Gigerenzer, G. (2010). From recognition to decisions: Extending and testing recognition-based models for multi-alternative inference. Psychonomic Bulletin & Review, 17, 287–309. doi:10.3758/PBR.17.3.287

The first in-text citations to each of these articles would be as follows:

  • (Marewski, Gaissmaier, & Gigerenzer, 2010)
  • (Marewski, Gaissmaier, Schooler, Goldstein, & Gigerenzer, 2010)

Now, what about subsequent in-text citations? Usually we would abbreviate studies with three or more authors to the first author name plus et al. (Latin for “and others”); however, doing so here would produce two Marewski et al. (2010) citations, leaving the reader unable to tell which one you mean. The solution is to spell out as many names as necessary (here, to the third name) upon subsequent citations to tell the two apart: 

  • (Marewski, Gaissmaier, & Gigerenzer, 2010)
  • (Marewski, Gaissmaier, Schooler, et al., 2010)

Notice that for the first reference, this means that all citations to this source will include all three names. For the second reference, the two remaining names can be abbreviated to et al. (Note, however, that if only one name remains to distinguish the references, that name must be spelled out with all the rest because et al. is plural—it cannot stand for only one name. This topic will be elaborated upon in an upcoming post.)

For more information and examples of citing references in text, see Chapter 6 of our sixth edition Publication Manual (pp. 174–179). You may also be interested in our primer on how in-text citations work.

October 06, 2011

Citing a Test Database


 By Anne Breitenbach

Some time ago, we had a post that explained how to find a DOI and provided a brief YouTube video of the process. We asked at the time for requests for tutorials about APA Style that could be useful. In response to that request, we were asked to create tutorials to explain how to cite content from two new databases APA is launching in September. The first of these, PsycTESTS, is a research database that provides descriptive and administrative information about tests, as well as access to some psychological tests, measures, scales, and other assessments. PsycTESTS is interesting in that it’s an example of citing the record itself, available only from a unique database, and not the test or supporting literature.

Take a look:


September 29, 2011

How to Cite a Musical Score

by Jeff Hume-Pratuch

JeffSheet music may not be the first thing you think of citing in APA Style. However, there is a large body of research on the topic of music and emotion, not to mention the specialty of music therapy. And where there is research, there must be citation!

Basically, a musical score is analogous to a book. The underlying format is as follows:

Composer, A. A. (Date). Title of work. Location: Publisher.

However, you may need to include a little more information in square brackets to identify for the reader which score you used (e.g., the vocal vs. the orchestral score):

Picker, T. (Composer), & McClatchy, J. D. (Librettist). (1995). 
An opera in two acts [Score and parts]. Mainz,
Germany: Schott Helicon.

Text citation: (Picker & McClatchy, 1995)

If you're using something like a Dover reprint of an old score, there’s no need to include the information about the original publishing company, but do include the original publication date:

Haydn, F. J. (2001). The creation. Mineola, NY: Dover. (Original work 
published 1798)

Text citation: (Haydn, 1798/2001)

Your reference should contain only the information needed to help your reader find the source you used. Aside from composer, date, title, and location, most of the necessary information can be included in square brackets after the title. However, some classical composers’ works are known by unique catalogue numbers, and these should be included as part of the title:

Mozart, W. A. (1970). Die Zauberflöte [The magic flute], K. 620 [Vocal 
score]. Munich, Germany: Becksche Verlagsbuchhandlung. (Original
work published 1791)

Text citation: (Mozart, 1791/1970)

Do you have a baffling reference that you’re not sure how to cite? Take a look at our series on creating your own reference, or e-mail us at styleexpert@apastyle.org

September 15, 2011

Best of the APA Style Blog: Fall 2011 Edition

Chelsea blog 2
by Chelsea Lee

Welcome back students and professors! Last fall we put together a “best of” feature on the blog, and this year we will continue the tradition with an updated set of posts from the APA Style Blog and our parent site, apastyle.org. We hope it will be helpful as new batches of students set upon the task of learning and implementing APA Style. You can get the full story in our sixth edition Publication Manual of the American Psychological Association and extra guidance via the links below.

Getting Started With APA Style

What is APA Style? APA 6th ed. Publication Manual

Why is APA Style needed?

A tutorial for those totally new to APA Style

A tutorial for those using the 6th edition manual for the first time

FAQs about APA Style

Get the APA Publication Manual (6th ed.) 


Sample Papers in APA Style

Sample Paper 1

Sample Paper 2

Sample meta-analysis paper

Sample published APA article


What To Do If Your Reference Isn’t in the Manual (a.k.a. How References Work)

Learn how references work


How To Cite...  

Diagnostic and Statistical Manual of Mental Disorders (DSM) 




Legal references (constitutions, etc.)

Paraphrased work

Secondary sources (sources you found in another source)


Website material


How to Format...

Running heads


Lists (lettered, numbered, or bulleted)





Still Need Help?

We have many resources to help you with your APA Style papers, and we think that you will find most questions are addressed in the Publication Manual (read Chapters 6 and 7 especially for help with references), on the blog, or in our FAQ. Please contact us if you need further assistance and we’ll be happy to help.

Finally, if you’re interested in receiving periodic tips about APA Style and notifications about new blog content, you can also keep in touch with us on Facebook and Twitter

September 08, 2011

Group Authors

Timothy McAdoo by Timothy McAdoo

In 2010, the estimated number of websites was 255 million. That translates to a staggering number of individual webpages. Who’s writing all those pages? And, how should you cite them in APA Style?

In this post, I’ll focus on just one possibility: group authors.  Although the “who” element for many references is an individual author or authors, “who” can also be a group author. This is often the case for white papers, press releases, and information pages (e.g., “About Us”) on company websites.

For example, the "about" page on the American Psychological Association site (http://www.apa.org/about/) was surely written by one or more real people. But, because no individual byline is listed and because this resides on the organization’s webpage, you would reference it as a group author. That is, the “who” in your reference is a group author.


American Psychological Association. (n.d.). About APA. Retrieved from

Notice that the author portion still ends with a period.

In the reference, spell out the full group author name.  Though you may choose to abbreviate the author name in text, spell it out in the reference list.

In your text, use the author–date format for citations. In this example, the author is “American Psychological Association” and the date is “n.d.”


    According to the American Psychological Association (n.d.), “psychology is a diverse discipline, grounded in science, but with nearly boundless applications in everyday life” (Definition of "Psychology," para. 1).

If you include the citation many times in your paper, you might want to abbreviate the group author name. If so, this introduction should be included with the first use in text:


    According to the American Psychological Association (APA, n.d., Definition of "Psychology," para. 1), “psychology is a diverse discipline, grounded in science, but with nearly boundless applications in everyday life.”

If you decide to abbreviate, do so consistently throughout the paper. Spelling out the name in some sections and abbreviating in others can confuse the reader.

Note that you are not required to abbreviate, even if the group author name appears frequently in your text. The Publication Manual (p. 176) recommends writing out the name of group authors, even if used many times in your text, if the group author name is short or “if the abbreviation would not be readily understandable.”

July 28, 2011

How to Cite the DSM in APA Style

Jeff by Jeff Hume-Pratuch

If you are working in any field that involves human behavior, sooner or later you will need to cite the Diagnostic and Statistical Manual of Mental Disorders (DSM). Published by the American Psychiatric Association (a.k.a. “the other APA”), the DSM provides a set of common criteria and language for talking about dysfunctions of the mind and emotions.

From the beginning, the DSM has been widely used as a guide by state and federal agencies for the reporting of public health statistics and the fulfillment of legislative mandates, as well as its use as a classification guide for research and clinical psychologists.

The DSM has gone through five revisions since it was first published in 1952, and each of those revisions has included substantial changes in structure and definitions. Some of these have been fairly controversial, such as the attempt to remove the term neurosis from DSM-III and the varying treatment of sexual disorders. A new edition (DSM-5) is in preparation, with a projected release date of May 2013, and major changes have been proposed for it as well.

Because of these changes and their effects on areas as disparate as longitudinal research parameters and health insurance benefits, it’s important to be precise when citing the DSM. Below are some guidelines to use in citing the most recent edition.

Citation Examples

American Psychiatric Association. (2000). Diagnostic and statistical 
manual of mental disorders
(4th ed., text rev.). Washington, DC: Author.

When a DOI is available, provide it after the publisher information. Individual chapters and other book parts are also assigned DOIs.

American Psychiatric Association. (2000). Diagnostic and statistical
manual of mental disorders
(4th ed., text rev.).
American Psychiatric Association. (2000). Appendix I: Outline for
cultural formulation and glossary of culturebound syndromes. In
Diagnostic and statistical manual of mental disorders (4th ed.,
text rev.). doi:10.1176/appi.books.9780890423349.7060

In text, cite the name of the association and the name of the manual in full at the first mention in the text; thereafter, you may refer to the traditional DSM form (italicized) as follows:

DSM–III (1980) 3rd ed.
DSM–III–R (1987) 3rd ed., revised
DSM–IV (1994) 4th ed.
DSM–IV–TR (2000) 4th ed., text rev.

After you have spelled out the name of the manual on first mention in the text, format the parenthetical citation as follows:

(3rd ed.; DSM–III; American Psychiatric Association, 1980)
(3rd ed., rev.; DSM–III–R; American Psychiatric Association, 1987)
(4th ed.; DSM–IV; American Psychiatric Association, 1994)
(4th ed., text rev.; DSM–IV–TR; American Psychiatric Association, 2000)

What About DSM-5?

The DSM-5 hasn’t been released yet, but there’s been much discussion of the proposed content. If necessary, refer to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5) in text when you cite these discussions. We’ll be back in May 2013 with tips on how to cite the DSM-5 itself, so mark your calendar!

UPDATE: DSM-5 has arrived! Go here for information on how to cite it.

June 16, 2011

Finding (and Using) Page Numbers for Kindle Books

Jeff by Jeff Hume-Pratuch

There’s no question that e-books make up a rapidly increasing segment of the publishing world. Amazon.com’s Kindle dominates this market, with hundreds of thousands of titles available in formats that can be read not only on the Kindle but on millions of iPads, iPhones, Blackberries, and Android devices as well.

Although the Kindle (and other e-book readers) are wonderfully portable, there has been one drawback to their use in research and scholarly writing: no page numbers. Instead, the device presents a number that roughly corresponds to the amount of text you’ve read. This number varies depending on the size of your display and the font settings you use; it has no relation to the pagination of the printed text.

Why Is This a Problem?

APA Style requires a page citation or paragraph number for directly quoted material (see the APA Publication Manual, 6th ed., pp. 170-171) to meet the overall goal of documentation, which is to fully credit your sources and allow your reader to retrieve them. A reader who picks up the same edition of a book you used can quickly turn to the exact source of your quotation. But because the Kindle location number depends on display and font size, readers sent to “Locations 2356-2445” may scroll in vain if they are using a different model or their settings are different from yours.

While the Publication Manual (pp. 170-172) provides some workarounds for citing unpaginated material (as outlined in this post), the only digital documents with real page numbers have been PDFs—until now, that is.

The Solution

In March, Amazon.com announced that the latest Kindle will display page numbers that correspond to those in the printed original of a digital book. If you have a Kindle 3G, you can view these page numbers by pressing the Menu button. The ISBN number of the original book is displayed on its product information page at Amazon.com. These page numbers meet the requirements for citations in APA Style.

Unfortunately, this is not a complete solution. If you have a Kindle 2, KindleDX, or other models, you won’t be able to see the page numbers. Amazon has no immediate plans to make this feature backward compatible, and so far the distributors of other devices (such as the Nook or Sony Reader) have not introduced similar features. However, for the users of the Kindle 3G, this is a great step forward.

June 03, 2011

How Do You Cite an E-Book (e.g., Kindle Book)?

Chelsea blog 2

by Chelsea Lee

E-books come in a variety of formats (e.g., Kindle, Adobe Digital Editions, EPub, HTML, and more) and can be read on a variety of devices (e.g., e-readers like the Kindle, Nook, and Sony Reader, as well as on personal computers and mobile devices through online portals such as NetLibrary, ebrary, and Google Books). This post shows how to cite any e-book in APA Style.

Reference List Entries

The reference list entry for a whole e-book should include elements of author, date, title (with e-reader book type in square brackets if applicable; italicize the title but not the bracketed material), and source (URL or DOI):

Author, A. A. (Year). Title of book [E-reader version, if applicable]. Retrieved from http://xxxxx

Author, A. A. (Year). Title of book [E-reader version, if applicable]. doi:xxxxx

  • If the book was read or acquired through an online library (e.g., Google Books, ebrary, NetLibrary) and not on an e-reader device, omit the bracketed information from the reference.

The reference list entry for a chapter in an edited e-book should be written as follows:

Author, A. A. (Year). Title of chapter. In B. B. Editor (Ed.), Title of book [E-reader version, if applicable] (pp. xxx–xxx). Retrieved from http://xxxxx

Author, A. A. (Year). Title of chapter. In B. B. Editor (Ed.), Title of book [E-reader version, if applicable] (pp. xxx–xxx). doi:xxxxx

  • If the e-book chapter does not have page numbers, omit that part of the reference.
  • To determine whether you need to cite the whole book or just a chapter, please see this post

In-Text Citations

For in-text citations of paraphrased material, provide the author and date, as for any APA Style reference. To cite a direct quotation, also provide page numbers if the e-book has page numbers. If there are no page numbers, you can include any of the following in the text to cite the quotation (see section 6.05 of the Publication Manual, pp. 171–172):

  • a paragraph number, if provided; alternatively, you can count paragraphs down from the beginning of the document; 
  • an overarching heading plus a paragraph number within that section; or 
  • an abbreviated heading (or the first few words of the heading) in quotation marks, in cases in which the heading is too unwieldy to cite in full.

A Note on Kindle Page Numbers and Location Numbers 

As of March 2011, many Kindle books now have real page numbers that correspond to those in print editions (as far as we know, this applies only for Kindle third generation products and going forward). These real page numbers are appropriate to use in academic citation (as are the page numbers of other paginated e-books). Kindle "location numbers," however, should not be used in citations because they have limited retrievability. Instead, for any e-book without page numbers, APA recommends the method described above for citations of directly quoted material.

See these links for further discussion of Kindles, e-books and e-book chapters, and citing unpaginated material, and see Publication Manual section 7.02 (pp. 202–205) for more examples.

May 26, 2011

A Marginal Note

More Tales from the Style Expert Inbox

.rev2 by Jeff Hume-Pratuch

Dear Style Expert,

I would like a clarification about the margins for an APA Style paper. The APA Publication Manual (6th ed.) says to “leave uniform margins of at least 1 in. (2.54 cm) at the top, bottom, left, and right of every page” (p. 229). I believe the correct thing to do is to space 1 in. at the top margin, then single space down and insert the running head. Some of my students are using a ½ in. margin for the top of the page, then single spacing down to type in the header, followed by a double space where the text of the paper begins. Who is right here? A lot of grades are riding on this.

—Inquiring Instructor

Dear Inquiring,

Typist Unless you’re teaching at Luddite State (where manual typewriters are a must), no one should be “spacing down” anything. The APA Publication Manual (6th ed.) does direct authors to use a 1-in. margin (p. 229), but it also directs them to “use the automatic functions of your word-processing program to generate headers” (p. 230). That means there’s no need to adjust the spacing around the header—it’s automatic!

Just set your margins at 1 in. (2.54 cm) and use the default setting for headers in your word-processing program. Voila! Your paper is correctly formatted in APA Style.

Dear Style Expert,

Now my whole study group is extremely confused, because your instructions seem to contradict the sample papers in the Publication Manual. It looks like there is more margin at the top of sample p. 4 than sample p. 3, and some of the pages are cut off at the bottom. What gives?
—Going Cross-Eyed in Cincinnati

Dear Cross-Eyed,

The sample papers are illustrations, not scale models. Just enough of each page is shown to illustrate the rules that are called out in the attached boxes. They’re not intended to show every point of APA Style, however, and you certainly can’t deduce margin guidelines from them. Fortunately, those guidelines are clearly stated on pp. 229–230 of the Publication Manual. If there ever appears to be a contradiction between an illustration and the text, follow the text.

Dear Style Expert,

Why, that’s crazy talk! A margin is empty space. If you have a 1-in. margin, then there should be 1 in. of empty space at the top of the page, with no headers in it.

—Marginal Maniac

Dear Marginal,

Think of it this way: The margin is, by definition, the part of a page outside the main body of text. The running head (again, by definition) is not part of the main body of text. Therefore, it is included in the margin, not below it.

Got a Question?

If you have a question (marginal or otherwise) about APA Style that hasn’t been answered yet, post it in the comments here. We’ll do our best to demystify it for you!

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