Simple Interactive Statistical Analysis
The sample size help page has moved o this location.
Sample size procedure to calculate the size of a sample necessary to compare two independent samples, one sample against a fixed value or parameter and sample size calculation for correlated or paired samples. It is also possible to calculate the sample size for an equality analysis. The user can specify any power (error 2) or alpha (error 1) value. Useful for the analysis of randomized controlled trials (RCT).