Reporting Descriptive Statistics in APA style
Describing the results of statistical analyses is done in a “Results” section of an APA-style research paper. Although you are not writing full Results sections for our lab class, it is good practice to work on writing up discussions of data in the format typically used for such sections. This will help you when you have to read research papers and when you do have to write your own paper in other courses!
A couple of general notes about discussing numbers:
- Data are often presented in parentheses, usually in order to make the description more concise and easier to “read” like a typical sentence. Just like any other parenthetical comment in a sentence, that means that you can skip over that information (what is in parentheses) and the sentence still makes complete sense (just like this one does). The information in parentheses is still important, but it is sort of secondary to understanding the meaning of the content. For example, standard deviations are often presented in parentheses after reporting means.
- Numbers are typically reported to two decimal places.
APA style is past tense (because you are reporting on results of a study that has already occurred).
APA style would be to italicize any symbols that have statistical meaning (like M, p, etc.). However, you do not need to do this for our lab assignments as formatting is somewhat limited within SPSS annotations.
Here are some examples showing how data including means (M), standard deviations (SD), and other descriptive statistics might be presented in APA style. The first two examples report the mean in the sentence and the SD in parentheses. The second two examples report both the M and SD in parentheses. Either works, depending on how you decide to form/frame the sentence!
- The average age of students was 19.22 years (SD = 3.45).
- Psychology majors had an average intelligence score of 105.75 (SD = 15.2), which was lower than the average score of 110.12 (SD = 14.8) for biology majors.
- The sample as a whole was relatively young (M = 19.22, SD = 3.45).
- Males reported about the same levels of anxiety (M = 5.22, SD = 1.43) as did females (M = 5.15, SD = 1.29).
- Nearly half (49.2%) of the sample was married.
Ms and SDs are the most commonly reported descriptive statistics in research papers, but if you are asked to report sample sizes, medians, ranges, or other statistics in our lab assignments, you can just spell those words out and add them to the content in similar ways like these examples:
- The 58 psychology majors in the sample had an average intelligence score of 105.75 (SD = 15.2) and a median score of 102. The 43 biology majors had slightly higher intelligence scores, with an average of 110.12 (SD = 14.8) and a median of 106.
- The sample as a whole was relatively young (M = 19.22, SD = 3.45, range = 13-28).
What APA Results sections do NOT do is write out the full wording for all statistics presented. That is, something like the following would NOT be APA Style:
There were xx males in the data and xx females. The average age for the males was xx and the standard deviation was xx. The average age for the females was xx and the standard deviation was xx. The males ranged from age xx to age xx and the females ranged from age xx to age xx.
Do you see how much longer and more cumbersome these sentences are to read? APA style is very concise and would report all of that information in potentially one (or maybe two, depending on how you word it) sentences, as follows:
The average age for males (N = xx, M = xx, SD = xx, range xx-xx) was similar to the average age for females (N = xx, M = xx, SD = xx, range xx-xx).
Much better, right?