More complete analyses

Prism now reports the reciprocal of the relative risk and odds ratio, and their confidence interval. Depending on the meaning of the rows and columns, the reciprocal may be more meaningful to you.

When you choose to report the difference between proportions, its reciprocal called the Number Needed to Treat (NNT) is also computed along with  its confidence interval.

Choice of algorithms

Prism offers new algorithms when computing the confidence interval of a proportion, the difference between two proportions, the relative risk, or the odds ratios.

The methods used by prior versions were simple approximations, and the improved methods Prism now offers produce narrower intervals that still provide the desired confidence level. We suggest you use them routinely.