Repeated Measures ANOVA Calculator
Test change across three or more time points or conditions measured on the same people, with sphericity checks and corrected degrees of freedom.
Updated · By Bibin XavierData 24 × 5
| Patienttext · 24 levels | Week_0numeric | Week_4numeric | Week_8numeric | Week_12numeric |
|---|---|---|---|---|
| P01 | 10 | 8.5 | 8.4 | 7.9 |
| P02 | 7.7 | 6.3 | 5.3 | 7.1 |
| P03 | 9 | 7 | 6.7 | 7.7 |
| P04 | 6.7 | 5.7 | 4.8 | 3.3 |
| P05 | 8.7 | 6.7 | 7.5 | 6.2 |
| P06 | 6.8 | 4.9 | 3.5 | 5 |
| P07 | 8.2 | 7.3 | 4.8 | 6.4 |
| P08 | 7.8 | 6 | 5.9 | 4.8 |
Variables and options
Results
24 rows · example dataDescriptive statistics
| Condition | n | M | SD | 95% CI |
|---|---|---|---|---|
| Week_0 | 24 | 7.38 | 1.30 | [6.83, 7.93] |
| Week_4 | 24 | 5.88 | 1.08 | [5.43, 6.34] |
| Week_8 | 24 | 5.45 | 1.25 | [4.92, 5.97] |
| Week_12 | 24 | 5.30 | 1.44 | [4.69, 5.90] |
Mauchly’s test of sphericity
| Within-subjects effect | Mauchly’s W | χ² | df | p | GG ε | HF ε |
|---|---|---|---|---|---|---|
| Condition | .656 | 9.15 | 5 | .103 | .783 | .878 |
Tests of within-subjects effects
| Correction | SS | df | MS | F | Error df | p | Partial η² |
|---|---|---|---|---|---|---|---|
| Sphericity assumed | 65.52 | 3.00 | 21.84 | 50.96 | 69.00 | < .001 | .689 |
| Greenhouse-Geisser | 65.52 | 2.35 | 27.89 | 50.96 | 54.03 | < .001 | .689 |
| Huynh-Feldt | 65.52 | 2.63 | 24.88 | 50.96 | 60.56 | < .001 | .689 |
Note. Error SS = 29.57, subjects SS = 120.00. Sphericity holds, so the uncorrected row is appropriate.
Pairwise comparisons (Bonferroni)
| Comparison | Mean difference | SE | t | df | pBonf |
|---|---|---|---|---|---|
| Week_0 − Week_4 | 1.50 | 0.13 | 11.53 | 23 | < .001 |
| Week_0 − Week_8 | 1.94 | 0.17 | 11.18 | 23 | < .001 |
| Week_0 − Week_12 | 2.09 | 0.20 | 10.44 | 23 | < .001 |
| Week_4 − Week_8 | 0.44 | 0.17 | 2.52 | 23 | .114 |
| Week_4 − Week_12 | 0.59 | 0.19 | 3.05 | 23 | .034 |
| Week_8 − Week_12 | 0.15 | 0.25 | 0.61 | 23 | 1.000 |
Means across conditions with 95% CI
Interpretation
Scores changed significantly across the 4 conditions, with a large effect (partial η² = .689).
How to cite this tool
Using these results in a thesis, journal article, report or class assignment? Please cite this free tool so others can find it. It keeps the site free.
APA 7
Xavier, B. (2026). Repeated Measures ANOVA Calculator [Web application]. FreeStatisticalTools.com. https://freestatisticaltools.com/repeated-measures-anova-calculator/
BibTeX
@software{xavier_repeatedmeasuresanova_2026,
author = {Xavier, Bibin},
title = {Repeated Measures ANOVA Calculator},
publisher = {FreeStatisticalTools.com},
year = {2026},
url = {https://freestatisticaltools.com/repeated-measures-anova-calculator/},
note = {Web application}
}Suggested sentence for your methods section: “The analysis was carried out with the free Repeated Measures ANOVA Calculator tool on FreeStatisticalTools.com (Xavier, 2026).”
What is a repeated measures ANOVA?
Repeated measures ANOVA compares three or more measurements taken on the same participants, such as scores at several time points. It accounts for differences between people and corrects for violations of sphericity.
When to use a repeated measures ANOVA
Use it for three or more measurements of the same outcome on the same subjects, such as scores at weeks 0, 4, 8 and 12.
Assumptions
- Approximately normal scores at each time point.
- Sphericity: equal variances of the differences between all pairs of conditions. Mauchly’s test checks this.
How to set up your data
Wide format: one row per subject and one column per condition. Rows with any missing value are excluded.
How to use this tool
- Enter your data. Paste columns from Excel, Google Sheets or SPSS with variable names in the first row, or upload a CSV or Excel file. The example data shows the expected layout.
- Choose the variables. Select the conditions and in order.
- Read the results. Results update automatically. Read the plain-English interpretation, then use Copy table to paste APA-style tables into Word and Copy for the results sentence.
How to report a repeated measures ANOVA in APA style
“Pain scores fell over time, F(2.41, 55.4) = 38.2, p < .001, η²p = .62, Greenhouse-Geisser corrected.”
Frequently asked questions
What is sphericity?
Sphericity means the variances of the differences between all pairs of conditions are equal. Mauchly’s test checks it; if it is significant, use a corrected F test.
Greenhouse-Geisser or Huynh-Feldt?
Use Greenhouse-Geisser when epsilon is below about .75 and Huynh-Feldt when it is higher, following Girden (1992).
How should the data be arranged?
Use wide format: one row per participant and one column per condition or time point, selected in order.
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