How to Report Statistical Results in APA Format

Getting the analysis right is only half the job. Reporting statistical results in APA format follows a set of conventions that reviewers know by heart, and deviations get noticed immediately. A missing degrees of freedom value, a leading zero where none belongs, or an unitalicized symbol signals carelessness before anyone reaches your conclusions.

This guide covers the formatting rules that apply to every statistic, then the specific notation for each test in a typical quantitative paper. It's about how the numbers are written. For what belongs in the section and how to organize it, see the guide to writing a results section.

The core pattern. Test statistic with degrees of freedom, then the p-value, then the effect size. For example: t(58) = 2.41, p = .019, d = 0.63.

Italics. Italicize statistical symbols written in Latin letters (M, SD, t, F, r, p, N). Leave Greek letters upright.

Leading zeros. Drop the leading zero for values that can't exceed 1, such as p-values and correlations. Keep it for values that can, such as means and Cohen's d.

P-values. Report exact values to two or three decimals. Use p < .001 only when the value falls below that.

APA Notation by Test: Quick Reference

This table covers the analyses in most quantitative papers. Each row shows the core reporting string and what should accompany it.

Analysis Core APA string Report alongside it
Independent-samples t test t(df) = value, p = value Group means and standard deviations, Cohen's d, confidence interval
Paired-samples t test t(df) = value, p = value Means and standard deviations at each time point, Cohen's d
One-way ANOVA F(df between, df within) = value, p = value Partial eta-squared, group means and standard deviations
Correlation r(df) = value, p = value Sample size, confidence interval, and r squared where useful
Simple linear regression b = value, t(df) = value, p = value Model fit as R² with its F test, confidence interval for b
Multiple regression Each predictor's b with its own t and p R² and adjusted R², the model F test, standardized betas
Logistic regression OR = value, 95% CI [lower, upper], p = value A model fit measure such as a pseudo R squared or classification accuracy
Chi-square test χ²(df, N = value) = value, p = value Cramer's V, and the observed cell counts or percentages
Mann-Whitney U U = value, p = value Median and interquartile range per group, rank-biserial correlation
Kruskal-Wallis H H(df) = value, p = value Median and interquartile range per group, epsilon-squared

The Rules That Apply to Every Statistic

Four conventions govern almost everything you'll write. Get these right and most of the rest follows.

Italicize the symbol, not the number

Statistical symbols written in Latin letters are italicized. That covers M, SD, t, F, r, p, d, N, n, and R². The numbers that follow stay upright. Greek letters are the exception and are never italicized, so alpha, beta, chi-square, and eta-squared all stay in roman type.

This trips people up because word processors don't enforce it and statistical software doesn't output it. The italics have to be applied by hand, which is exactly why a manuscript missing them looks rushed.

The leading zero rule

Drop the zero before the decimal point when a value can never exceed 1. That covers p-values, correlation coefficients, and proportions of variance like eta-squared and R squared. So you write p = .03 and r = .48, not 0.03 and 0.48.

Keep the leading zero when a value can exceed 1. Means, standard deviations, test statistics, and Cohen's d all qualify, since d has no upper bound. So d = 0.63 keeps its zero while r = .63 does not, even though the digits look identical.

Decimal places

Two decimal places is the default for most statistics, including means, standard deviations, test statistics, and effect sizes. P-values take two or three, with three reserved for values close to the threshold where the extra digit carries information.

Round consistently across the whole paper. Reporting one mean to two decimals and another to three, with no reason for the difference, reads as inattention.

Degrees of freedom go in parentheses

Degrees of freedom follow the symbol in parentheses, before the equals sign: t(58), F(2, 87), r(118). Tests with two df values, like F, take both separated by a comma, with the numerator first.

Chi-square is the exception that also carries the sample size: χ²(2, N = 240) = 9.41. That's a rule reviewers in some fields check specifically, so it's worth getting right.

Reporting P-Values

Report the exact p-value rather than a threshold statement. Writing p = .034 tells the reader more than p < .05, and current APA guidance prefers it. The one time you use an inequality is when the value falls below .001, where you write p < .001 instead of chasing decimals.

Never write p = .000, which statistical software will happily display. A p-value is never exactly zero, only smaller than the software chose to print. That output should always be reported as p < .001.

Two related habits are worth avoiding. Don't describe a result as approaching significance, because a p-value of .07 either clears your threshold or doesn't. And reserve the word significant for its statistical meaning, using words like substantial or meaningful when you mean practical importance. For the underlying logic, see the guide to hypothesis testing.

Reporting Descriptive Statistics

Descriptive statistics usually appear in parentheses after the group they describe. The standard form pairs the mean with the standard deviation.

The intervention group scored higher on the post-test (M = 82.40, SD = 7.10) than the control group (M = 76.10, SD = 6.80).

Use capital N for the total sample and lowercase n for a subgroup. Percentages take the percent sign with no space, and a number is given alongside it when the base isn't obvious. For skewed or ordinal data, report the median and interquartile range instead, since the mean misleads there. The reasoning behind that choice is covered in the guide to standard deviation and variance.

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Reporting T-Tests

Give the group descriptives, then the test, then the effect size. A complete independent-samples report looks like this.

Tutored students (M = 82.40, SD = 7.10) outperformed controls (M = 76.10, SD = 6.80), t(18) = 2.03, p = .029, d = 0.91, 95% CI [0.02, 1.80].

For a paired test, the descriptives describe time points rather than groups, and it helps to name the direction of change. State which test you ran when it isn't obvious from the design, and say whether the test was one-tailed, since two-tailed is assumed by default. The tests themselves are covered in the guide to t-tests.

One convention on the name itself. APA writes it as a t test without a hyphen when it's a noun. It hyphenates only when the term modifies another noun, as in t-test results. Journals vary on how strictly they enforce this.

Reporting ANOVA

ANOVA reports carry two degrees of freedom values: the numerator first, then the denominator. Effect size for ANOVA is usually partial eta-squared, and naming it explicitly matters because plain eta-squared is a different quantity.

Teaching method had a significant effect on test scores, F(2, 87) = 5.67, p = .005, partial η² = .12.

A significant omnibus F tells the reader that at least one group differs, so report the post-hoc comparisons that identify which. Name the correction you applied, such as Bonferroni or Tukey, since an uncorrected set of pairwise tests inflates the error rate. Factorial designs report each main effect and each interaction on its own line, in that order. See the guide to ANOVA for the tests.

Reporting Correlation

Correlations take degrees of freedom rather than the raw sample size, and df is N minus 2 for a Pearson correlation. The coefficient drops its leading zero.

Study hours correlated positively with exam score, r(118) = .48, p < .001, 95% CI [.33, .61].

Because r is already a standardized effect size, no separate effect size is needed. Adding r squared is useful when you want to state the shared variance directly. When you report many correlations at once, a correlation matrix table is clearer than a paragraph of coefficients. For coefficient selection and reporting in depth, see using correlation coefficients in research papers, and for the mechanics, what the correlation coefficient measures.

Reporting Regression

Regression reporting has two layers: the model as a whole, then each predictor. Report the model first.

The model significantly predicted exam score, R² = .98, F(1, 6) = 277.06, p < .001. Study hours was a significant predictor, b = 2.69, 95% CI [2.29, 3.08], t(6) = 16.65, p < .001.

Lead with the unstandardized coefficient b, since it's the one interpretable in your variables' units. Standardized betas belong alongside it when you want to compare predictors measured on different scales. For models with several predictors, report adjusted R² as well. Put the coefficients in a table rather than prose once you pass three or four.

Logistic regression reports odds ratios rather than raw coefficients, always with their confidence intervals. An interval spanning 1 means the predictor isn't significant, no matter how the point estimate looks. The models are covered in the guides to simple linear regression, multiple regression, and logistic regression.

Reporting Chi-Square and Non-Parametric Tests

Chi-square carries both degrees of freedom and the sample size inside the parentheses, and the Greek chi stays upright.

Program completion differed by enrollment status, χ²(2, N = 240) = 9.41, p = .009, Cramer's V = .20.

Rank-based tests follow the same pattern with their own statistics: U for Mann-Whitney, H with degrees of freedom for Kruskal-Wallis. The important difference is in the descriptives. Because these tests work on ranks, describe the data with medians and interquartile ranges rather than means and standard deviations. Reporting a mean alongside a rank-based test reintroduces the sensitivity to skew you switched tests to avoid. See the guide to non-parametric tests.

Effect Sizes and Confidence Intervals

Journals across psychology, education, and health now expect an effect size with every significance test, and many expect a confidence interval too. Both go at the end of the reporting string, after the p-value.

Name the specific measure rather than writing effect size generically, since Cohen's d, Hedges' g, and partial eta-squared aren't interchangeable. Confidence intervals use square brackets with the limits separated by a comma, and the confidence level stated once: 95% CI [0.02, 1.80]. If every interval in a paragraph is at 95 percent, say so at the start rather than repeating it.

One thing effect sizes fix that p-values can't: significance depends heavily on sample size, so a trivial effect can reach significance in a large study. Reporting the magnitude is what keeps that visible. See the guide to effect sizes for which measure pairs with which test.

When to Use a Table Instead of Text

Prose works for a handful of statistics. Past that, a table is clearer and journals prefer it. The usual triggers are a correlation matrix, a regression with several predictors, and descriptives across multiple groups or time points. Any set of results the reader will want to compare across rows belongs in one too.

  • Don't duplicate. If a value is in a table, don't restate it in the text. Highlight the finding and point the reader to the table.
  • Number and title every table. Tables are numbered in order of first mention, with a brief italicized title beneath the number.
  • Reference every table in the text. A table that no sentence points to will be queried in review.
  • Note what the symbols mean. Use a general note beneath the table to define abbreviations and state the significance convention.

Common Mistakes

  • Writing p = .000. Software output, not a real value. Report p < .001.
  • Leaving symbols unitalicized. Statistical software doesn't italicize, so it has to be done by hand.
  • Leading zeros on p-values and correlations. Both are bounded by 1, so both drop the zero.
  • Omitting degrees of freedom. A test statistic without its df can't be evaluated or replicated.
  • Reporting significance without an effect size. Most journals now treat this as incomplete reporting.
  • Saying a result approached significance. A p-value either clears the threshold or it doesn't.
  • Mixing eta-squared and partial eta-squared. They're different quantities and partial values run larger. Label which one you mean.
  • Interpreting in the results section. Report the numbers there and save what they mean for the discussion.

Where to Go Next

This guide covers notation. For what belongs in the section and how to organize it, see writing a results section. For APA citation and reference formatting, which follows a separate set of rules, see the APA citation guide. For the sample size decisions that shape what you can report, see calculating sample size. The guide to Type I and Type II errors covers the errors behind those decisions.

When the analysis is written up, the results section is where a subject-matter editor earns their place. A reviewer who spots a p-value reported as .000, or an effect size that doesn't match the test, will question everything around it. Editor World's academic editing, dissertation editing, and journal article editing services include review of statistical reporting. You choose your own editor by field, so the person reading your results knows your discipline's conventions.


Frequently Asked Questions

How do you report statistical results in APA format?

Report the test statistic with its degrees of freedom, then the p-value, then the effect size. A t-test result reads: t(58) = 2.41, p = .019, d = 0.63. Italicize statistical symbols written in Latin letters and leave the numbers upright. Degrees of freedom go in parentheses right after the symbol, and you give the group means and standard deviations alongside. Confidence intervals follow the effect size in square brackets.

Should p-values have a leading zero in APA style?

No. APA drops the zero before the decimal for any value that can't exceed 1. That covers p-values, correlations, and proportions of variance like R² and eta-squared. So you write p = .03, not 0.03. Values that can exceed 1 keep it, including means, standard deviations, test statistics, and Cohen's d, which has no upper bound.

How do you report a p-value of zero in APA format?

Report it as p < .001. Software often displays p = .000, but a p-value is never exactly zero. That display just means the value is smaller than the software chose to print. Writing p = .000 is a common error and an easy one for a reviewer to spot. Everywhere else, report exact p-values to two or three decimals rather than an inequality.

Which statistical symbols are italicized in APA style?

Symbols written in Latin letters are italicized. The set is M, SD, t, F, r, p, d, N, n, and R². The numbers after them stay upright. Greek letters are never italicized, so alpha, beta, chi-square, and eta-squared stay in roman type. Statistical software doesn't italicize its output, so you have to add the formatting yourself.

Do you have to report effect sizes in APA format?

Most journals in psychology, education, and health now expect one with every significance test, and many want a confidence interval too. Significance depends heavily on sample size, so a difference too small to matter can still reach significance in a large study. The effect size reports the magnitude, which is what lets a reader judge whether the finding means anything. Name the specific measure, since effect sizes aren't interchangeable.

When should results go in a table instead of the text?

Use a table when the reader will want to compare values across rows, or when prose would turn into a list of numbers. The usual cases are a correlation matrix, a regression with several predictors, and descriptives across multiple groups or time points. Don't repeat in the text what the table already shows. Highlight the key finding and point the reader to it. Every table needs a number, a brief title, and a mention in the text.


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