Fisher's exact test for a 2x2 table
Fisher's exact test
Fisher's exact test in the Tests menu is used to calculate an exact P-value for a 2x2 frequency table with small number of expected frequencies, for which the Chi-squared test is not appropriate.
The data (representing number of cases) for the 2x2 table are entered in the dialog box.
Example: treatment A resulted in 6 successes and 1 failure (6/7 = 85.7%) whereas treatment B resulted in 2 success and 8 failures (2/10 = 20%). The following is entered in the dialog box:
The P-value (the probability of obtaining the observed result or a more extreme result) is calculated when you press the Test button.
The result, P=0.015, indicates that the 2 treatments gave significantly different results.
In the Comment input field you can enter a comment or conclusion that will be included on the printed report.
- Altman DG (1991) Practical statistics for medical research. London: Chapman and Hall.
- Fisher's exact test on Wikipedia.