Computes sample size for Student's t-test and for the Wilcoxon-Mann-Whitney test for categorical data. The t-test function allows paired and unpaired (balanced / unbalanced) designs as well as homogeneous and heterogeneous variances. The Wilcoxon function allows for ties.
To install the development version of the samplesize package, it is easiest to use the devtools package:
install.packages("devtools") # if needed.. library(devtools) install_github("samplesize", "shearer") library(samplesize)