TABLE 2—

Software for Sample Size Calculations in Parallel-Arm GRTs

Software	Functionality
PASSa	Sample size calculations for GRTs comparing 2 means (noninferiority, equivalence, or superiority), 2 proportions (noninferiority, equivalence, or superiority), 2 Poisson rates, and a log-rank test
nQueryb	Comparison of 2 means, proportions, and rates
Statac	User-provided command clustersampsi; can compute sample size for continuous, binary, and rate outcomes for 2-sided tests in equal-sized arms
Rd	Package CRTSize for comparing 2 means or 2 binary proportions
SASe	No built-in functionality at this time
Calculator	For some simple designs, parameter values can be plugged into formulas provided in textbooks

Note. GRT = group-randomized trial; PASS = Power and Analysis Software.

^aVersion 15 (NCSS Statistical Software, Kaysville, UT).

^bVersion 7 (Statsols, Boston, MA).

^cVersion 14 (StataCorp LP, College Station, TX).

^dVersion 3.3.2 (R Foundation for Statistical Computing, Vienna, Austria).

^eVersion 9.4 (SAS Institute, Cary, NC).