How to use
- Enter event and non-event counts for group A and group B.
- Choose the confidence level and decimal places.
- Read the risk difference, interval, and warnings before moving to ARR / NNT or RR comparison pages.
Wave 31 statistics entry
Add interval context to one risk difference
The share URL stores only confidence and decimal settings.
How to choose between nearby pages
Use risk difference when the point estimate alone is enough. Use this page when the same 2x2 table now needs interval width. Move to ARR / NNT if the next question is people-needed wording, or to risk ratio confidence interval if you need a ratio-based comparison instead.
FAQ
What does this page calculate?
It reads the risk difference from one 2x2 table and adds a confidence interval at 90%, 95%, or 99%.
How is this different from the quick risk-difference page?
The quick risk-difference page is the shortest route to the point estimate only. This page keeps the same 2x2 table input but adds confidence-interval context.
Does a zero cell break the interval?
No. When a cell is zero, the interval uses a small continuity correction so the interval can still be shown in a stable way.
Does the share URL include my counts?
No. The share URL stores only light settings such as decimal places and confidence level. Your counts stay in your browser.