PS is an interactive computer program for performing statistical power and sample size calculations.

The user specifies the alternative hypothesis in terms of differing response rates, means, survival times, relative risks, or odds ratios.

A description of each calculation, written in English, is generated and may be copied into the user's documents.

[3] The program can generate graphs of the relationships between power, sample size and the detectable alternative hypothesis.

Reviews of this program have been published by McCrum-Gardner,[10] Thomas and Krebs,[11] Stawicki[12] and Pezzullo.