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## Statistics in APA

Summary:

APA (American Psychological Association) style is most commonly used to cite sources within the social sciences. This resource, revised according to the 6th edition, second printing of the APA manual, offers examples for the general format of APA research papers, in-text citations, endnotes/footnotes, and the reference page. For more information, please consult the Publication Manual of the American Psychological Association, (6th ed., 2nd printing).

When including statistics in written text, be sure to include enough information for the reader to understand the study. Although the amount of explanation and data included depends upon the study, APA style has guidelines for the representation of statistical information:

• Do not give references for statistics unless the statistic is uncommon, used unconventionally, or is the focus of the article
• Do not give formulas for common statistics (i.e. mean, t test)
• Do not repeat descriptive statistics in the text if they’re represented in a table or figure
• Use terms like respectively and in order when enumerating a series of statistics; this illustrates the relationship between the numbers in the series.

#### Punctuating statistics

Use parentheses to enclose statistical values:

...proved to be statistically significant (p = .42) with all variables.

Use parentheses to enclose degrees of freedom:

t(45) = 4.35
F(3, 87) = 2.11

Use brackets to enclose limits of confidence intervals:

89% CIs [3.45, 2.7], [-6.0, 3.89], and [-7.23, 1.89]

Use standard typeface (no bolding or italicization) when writing Greek letters, subscripts that function as identifiers, and abbreviations that are not variables.

Use boldface for vectors and matrices:

V, ∑

Use italics for statistical symbols (other than vectors and matrices):

t, F, N

Use an italicized, uppercase N to refer to a total population.

N = 328

Use an italicized, lowercase n to refer to a sample of the population.

n = 42