Chi-square test for a 2×2 table
Rows are the two groups. Columns are the two outcomes. Counts must be non-negative.
Expected counts: 22.5, 17.5, 22.5, 17.5.
Questions
What is a chi-square calculator used for?
This one tests whether two binary groups differ. Enter the four cells of a 2×2 table. The result is Pearson's chi-square with 1 degree of freedom and its p value.
When should I use Fisher's exact test instead?
Use Fisher's exact test when any expected count is under 5, or when the table is small. This page flags that case and links to the Fisher calculator.
Does this include Yates' correction?
No. The statistic is the uncorrected Pearson chi-square. Yates' correction makes the test more conservative and is not shown here.
Educational only. Not medical advice, not a regulatory determination, and not a substitute for qualified RA/QA, legal, clinical, or statistical counsel. Chi-square calculator does not submit to FDA, Notified Bodies, or IRBs.