Fisher’s exact test
Exact test of association for a 2×2 table.
When to use it
Use Fisher’s exact test on a 2×2 table when expected counts are small. It asks the same question as chi-square: are the two binary variables associated?
Assumptions
Both columns have exactly two levels. The test conditions on the row and column totals.
Running it in Tensr
Options
Prop
Type
Reading the output
A 2×2 of exposure and case status. The case rate was built only a little higher in the exposed row, on 90 people.
| exposed | No | Yes |
|---|---|---|
| No | 28 | 15 |
| Yes | 23 | 24 |
Fisher's exact test for exposed × case, n = 90. The primary result is not significant (p = .140). This is not large enough to treat the comparison this page is about as a reliable association. The result is non-significant: the data are still compatible with no effect. Metrics: Odds ratio = 1.948; 95% CI = [0.834, 4.552]; p (two-tailed) = .140; p (one-tailed) = .140.
Reporting (APA 7)
Fisher's exact test for exposed × case, n = 90. This result is not significant (p = .140). Report the estimate with that p, and do not describe the pattern as a reliable effect.
Coming from SPSS
Crosstabs → Exact → Fisher’s exact test. SPSS also prints a one-sided p. Tensr stores both p_value_two_tailed and p_value_one_tailed.