This utility calculates the sample size required for a cohort study, with specified levels of confidence and power and cohorts of equal size.

Inputs are the expected incidence in the unexposed cohort, the assumed relative risk, and the desired level of confidence and power for the detection of a significant difference between the two cohorts.

The program outputs the sample size required for the specified inputs. Also output is a summary table of sample sizes for a range of assumed incidence values and relative risks.