WMWSSP {rankFD}

Sample size computation methods for the Wilcoxon-Mann-Whitney test based on pilot data

Description

The function implements the sample size formula proposed by Happ et al. (see reference below). It estimates the sample size needed to detect the effect with pre-defined power at significance level alpha based on pilot data.

Usage

WMWSSP(x1, x2, alpha = 0.05, power = 0.8, t = 1/2)

Arguments

x1

advance information for the first group

x2

advance information for the second group

alpha

two sided type I error rate

power

power with the sample sizes of each group

t

proportion of subjects in the first group

Value

Returns a data frame

References

Brunner, E., Bathke A. C. and Konietschke, F. Rank- and Pseudo-Rank Procedures in Factorial Designs - Using R and SAS. Springer Verlag. Happ, M., Bathke, A. C., & Brunner, E. (2019). Optimal sample size planning for the Wilcoxon-Mann-Whitney test. Statistics in medicine, 38(3), 363-375.

Examples

x1 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2)
x2 = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3)
WMWSSP(x1,x2,0.05,0.8,0.5)