Chi-square and Fisher’s exact
Compare counts across categories, with the odds ratio and its interval.
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Paste straight from a spreadsheet. Any table works; 2×2 also gets Fisher’s exact test and an odds ratio.
Paste a table of counts — at least two rows and two columns.
Formula
χ² = Σ (|O − E| − c)² ÷ E, c = ½ on 2×2; Fisher sums hypergeometric tables at least as extremeModelChi-square, uncorrected
- The exact test for a 2×2 table — Journal of the Royal Statistical Society, 1922
- Continuity correction for the chi-square test — Supplement to the Journal of the Royal Statistical Society, 1934
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Report the proportions as well. “12 of 40 against 31 of 44” tells a reader more than any p-value attached to it.
About this tool
Tests a contingency table of counts. Chi-square with Yates’ correction on 2×2 tables, and Fisher’s exact test recommended automatically when expected counts fall below five — which is most bench data.
Related tools
- t-test calculator — Compare two groups and get the effect size and interval, not just a p-value.
Science last reviewed .