Reporting Statistics in APA Style | Guidelines & Examples
The APA Publication Manual is commonly used for reporting research results in the social and natural sciences. This article walks you through APA Style standards for reporting statistics in academic writing.
Statistical analysis involves gathering and testing quantitative data to make inferences about the world. A statistic is any number that describes a sample: it can be a proportion, a range, or a measurement, among other things.
When reporting statistics, use these formatting rules and suggestions from APA where relevant.
Table of contents
- Numbers and measurements
- Decimal places and leading zeros
- Formatting mathematical formulas
- Formatting statistical terms
- Reporting means and standard deviations
- Reporting chi-square tests
- Reporting z tests and t tests
- Reporting analysis of variance (ANOVAs)
- Reporting correlations
- Reporting regressions
- Reporting confidence intervals
- Other interesting articles
- Frequently asked questions about APA Style statistics
Numbers and measurements
In general, APA advises using words for numbers under 10 and numerals for 10 and greater. However, always spell out a number that appears at the start of a sentence (or rephrase).
You should always use numerals for:
- Exact numbers before units of measurement or time
- Mathematical equations
- Percentages and percentiles
- Ratios, decimals, and uncommon fractions
- Scores and points on scales (e.g., 7-point scale)
- Exact amounts of money
Units of measurement and time
Report exact measurements using numerals, and use symbols or abbreviations for common units of measurement when they accompany exact measurements. Include a space between the number and the abbreviation.
When stating approximate figures, use words to express numbers under 10, and spell out the names of units of measurement.
- The ball weighed 7 kg.
- The ball weighed approximately seven kilograms.
Measurements should be reported in metric units. If you recorded measurements in non-metric units, include metric equivalents in your report as well as the original units.
Percentages
Use numerals for percentages along with the percent symbol (%). Don’t insert a space between the number and the symbol.
Words for “percent” or “percentage” should only be used in text when numbers aren’t used, or when a percentage appears at the start of a sentence.
- Of these respondents, 15% agreed with the statement.
- Fifteen percent of respondents agreed with the statement.
- The percentage was higher in 2020.
Decimal places and leading zeros
The number of decimal places to report depends on what you’re reporting. Generally, you should aim to round numbers while retaining precision. It’s best to present fewer decimal digits to aid easy understanding.
The following guidelines are usually applicable.
| One decimal place | Two decimal places |
|---|---|
|
|
Use two or three decimal places and report exact values for all p values greater than .001. For p values smaller than .001, report them as p < .001.
Leading zeros
A leading zero is zero before the decimal point for numbers less than one. In APA Style, it’s only used in some cases.
Use a leading zero only when the statistic you’re describing can be greater than one. If it can never exceed one, omit the leading zero.
| Use a leading zero | Don’t use a leading zero |
|---|---|
|
|
- Consumers reported high satisfaction with the services (M = 4.1, SD = 0.8).
- The correlation was medium-sized (r = .35).
- Although significant results were obtained, the effect was relatively small (p = .015, d = 0.11).
Formatting mathematical formulas
Provide formulas only when you use new or uncommon equations. For short equations, present them within one line in the main text whenever possible.
Make the order of operations as clear as possible by using parentheses (round brackets) for the first step, brackets [square brackets] for the second step, and braces {curly brackets} for the third step, where necessary.
More complex equations, or equations that take more than one line, should be displayed on their own lines. Equations should be displayed and numbered if you will reference them later on, regardless of their complexity. Number equations by placing the numbers in parentheses near the right edge of the page.
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Formatting statistical terms
When reporting statistical results, present information in easily understandable ways. You can use a mix of text, tables, and figures to present data effectively when you have a lot of numbers to report.
In your main text, use helpful words like “respectively” or “in order” to aid understanding when listing several statistics in a sequence.
The APA manual provides guidelines for dealing with statistical terms, symbols and abbreviations.
Symbols and abbreviations
Population parameters are often represented with Greek letters, while sample statistics are often represented with italicized Latin letters.
Use the population symbol (N) for the total number of elements in a sample, and use the sample symbol (n) for the number of elements in each subgroup of the full sample.
In general, abbreviations should be defined on first use, but this isn’t always the case for common statistical abbreviations.
| Define | Don’t define |
|---|---|
|
|
| Use symbols for statistical terms | Use words for statistical terms |
|---|---|
| When directly referring to a numerical quantity or operator: M = 5.41 | In the main text: “the mean accuracy was higher…” |
Capitalization, italicization and hyphenation
Statistical terms such as t test, z test, and p value always begin with a lowercase, italicized letter. Never begin a sentence with lowercase statistical abbreviations.
These statistical terms should only be hyphenated when they modify a subsequent word (e.g., “z-test results” versus results of “z tests”).
You can form plurals of statistical symbols (e.g., M or p) by adding a non-italicized “s” to the end with no apostrophe (e.g., Ms or ps).
In general, the following guidelines apply.
| Italicize | Don’t italicize |
|---|---|
|
|
| Capitalize | Don’t capitalize |
|---|---|
| Names of effects or variables only when they appear with multiplication signs: Age × Sex effect | Lowercase statistical terms: t test, p value |
Parentheses vs. brackets
Always aim to avoid nested parentheses and brackets when reporting statistics. Instead, you should use commas to separate related statistics.
| Use parentheses (round brackets) | Use (square) brackets |
|---|---|
|
|
- Scores improved between the pretest and posttest (p < .001).
- Significant differences in test scores were recorded, F(1, 30) = 4.67, p = .003.
- (A previous meta-analysis highlighted low effect sizes [d = 0.1] in the field).
Reporting means and standard deviations
Report descriptive statistics to summarize your data. Quantitative data is often reported using means and standard deviations, while categorical data (e.g., demographic variables) is reported using proportions.
Means and standard deviations can be presented in the main text and/or in parentheses. You don’t need to repeat the units of measurement (e.g., centimeters) for statistics relating to the same data.
- Average sample height was 136.4 cm (SD = 15.1).
- The height of the initial sample was relatively low (M = 125.9 cm, SD = 16.6).
- Height significantly varied between children aged 5–7, 8–10, and 11–13. The means were 115.3, 133.5, and 149.1 cm, respectively.
Reporting chi-square tests
To report the results of a chi-square test, include the following:
- the degrees of freedom (df) in parentheses
- the chi-square (Χ2) value (also referred to as the chi-square test statistic)
- the p value
- A chi-square test of independence revealed a significant association between gender and product preference, Χ2(8) = 19.7, p = .012.
- Based on a chi-square test of goodness of fit, Χ2(4) = 11.34, p = .023, the sample’s distribution of religious affiliations matched that of the population’s.
Reporting z tests and t tests
For z tests
To report the results of a z test, include the following:
- the z value (also referred to as the z statistic or z score)
- the p value
- The participants’ scores were higher than the population average, z = 2.48, p = .013.
- Higher scores were obtained on the new 20-item scale compared to the previous 40-item scale, z = 2.67, p = .007.
For t tests
To report the results of a t test, include the following:
- the degrees of freedom (df) in parentheses
- the t value (also referred to as the t statistic)
- the p value
- Older adults experienced significantly more loneliness than younger adults, t(32) = 2.94, p = .006.
- Reaction times were significantly faster for mice in the experimental condition, t(53) = 5.94, p < .001.
Reporting analysis of variance (ANOVAs)
To report the results of an ANOVA, include the following:
- the degrees of freedom (between groups, within groups) in parentheses
- the F value (also referred to as the F statistic)
- the p value
- A one-way ANOVA demonstrated that the effect of leadership style was significant for employee engagement, F(2, 78) = 4.58, p = .013.
- We found a statistically significant main effect of age group on social media use, F(3, 117) = 3.19, p = .026.
Reporting correlations
To report the results of a correlation, include the following:
- the degrees of freedom in parentheses
- the r value (the correlation coefficient)
- the p value
- We found a strong correlation between average temperature and new daily cases of COVID-19, r (357) = .42, p < .001.
Reporting regressions
Results of regression analyses are often displayed in a table because the output includes many numbers.
To report the results of a regression analysis in the text, include the following:
- the R2 value (the coefficient of determination)
- the F value (also referred to as the F statistic)
- the degrees of freedom in parentheses
- the p value
The format is usually:
- SAT scores predicted college GPA, R2 = .34, F(1, 416) = 6.71, p = .009.
Reporting confidence intervals
You should report confidence intervals of effect sizes (e.g., Cohen’s d) or point estimates where relevant.
To report a confidence interval, state the confidence level and use brackets to enclose the lower and upper limits of the confidence interval, separated by a comma.
- Older adults experienced significantly more loneliness than younger adults, t(32) = 2.94, p = .006, d = 0.81, 95% CI [0.6, 1.02].
- On average, the treatment resulted in a 30% reduction in migraine frequency, 99% CI [26.5, 33.5].
When presenting multiple confidence intervals with the same confidence levels in a sequence, don’t repeat the confidence level or the word “CI.”
Other interesting articles
If you want to know more about statistics, methodology, or research bias, make sure to check out some of our other articles with explanations and examples.
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Frequently asked questions about APA Style statistics
- What statistical results do you need to report according to APA style?
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According to the APA guidelines, you should report enough detail on inferential statistics so that your readers understand your analyses.
Report the following for each hypothesis test:
- the test statistic value
- the degrees of freedom
- the exact p value (unless it is less than 0.001)
- the magnitude and direction of the effect
You should also present confidence intervals and estimates of effect sizes where relevant.
- How many decimal places do you use in APA style?
-
The number of decimal places to report depends on what you’re reporting. Generally, you should aim to round numbers while retaining precision. It’s best to present fewer decimal digits to aid easy understanding.
Use one decimal place for:
Use two decimal places for:
- Correlation coefficients
- Proportions
- Inferential test statistics such as t values, F values, and chi-squares.
- When should I use tables or figures to present numbers?
-
In APA style, statistics can be presented in the main text or as tables or figures. To decide how to present numbers, you can follow APA guidelines:
- To present three or fewer numbers, try a sentence,
- To present between 4 and 20 numbers, try a table,
- To present more than 20 numbers, try a figure.
Since these are general guidelines, use your own judgment and feedback from others for effective presentation of numbers.
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