Calculate Power and Sample Size for Two Sample Mean Tests

Power calculations are a critical component of any research study to determine the minimum sample size necessary to detect differences between multiple groups. Here we present an 'R' package, 'PASSED', that performs power and sample size calculations for the test of two-sample means or ratios with data following beta, gamma (Chang et al. (2011), ), normal, Poisson (Gu et al. (2008), ), binomial, geometric, and negative binomial (Zhu and Lakkis (2014), ) distributions.