How to use
- Enter event and non-event counts for group A and group B.
- Choose whether you need a two-sided, greater, or less exact read.
- Review the exact p-values first, then move to RR / OR / RD pages only if you also need effect-size framing.
Wave 32 statistics entry
Read an exact 2x2 p-value
The share URL stores only the selected tail and decimal places.
| A-event count | 2x2 table | Exact probability |
|---|
How to choose between nearby pages
Use Fisher exact test when the 2x2 table is small and the first question is an exact p-value. Use RR with CI, OR with CI, or RD with CI when the next question is interval width and effect-size framing after the exact-significance read.
FAQ
What does this page calculate?
It runs Fisher exact test on one 2x2 table and reports exact two-sided, greater, and less p-values together with the odds ratio.
When should I prefer Fisher exact test over chi-square?
Use Fisher exact test when the 2x2 table is small or sparse and you want an exact p-value instead of an asymptotic approximation.
Does the share URL include my table counts?
No. The share URL stores only light settings such as the selected alternative and decimal places. The counts stay in your browser.
Why does the odds ratio become infinity?
If one 2x2 cell is zero, the raw odds ratio can become 0 or infinity. Read the exact p-value first and treat the odds ratio as directional context.