size.test.mann: Sample size for a Mann-Whitney test

In statpsych: Statistical Methods for Psychologists

Sample size for a Mann-Whitney test

Description

Computes the sample size in each group (assuming equal sample sizes) required for the Mann-Whitney test with desired power. A planning value of the Mann-Whitney parameter is required. In a 2-group experiment, this parameter is the proportion of members in the population with scores that would be larger under treatment 1 than treatment 2. In a 2-group nonexperiment where participants are sampled from two subpopulations of sizes N1 and N2, the parameter is the proportion of all N1 x N2 pairs in which a member from subpopulation 1 has a larger score than a member from subpopulation 2.

Usage

size.test.mann(alpha, pow, p)

Arguments

alpha	alpha level for hypothesis test
pow	desired power
p	planning value of Mann-Whitney parameter

Value

Returns the required sample size for each group

References

\insertRef

Noether1987statpsych

Examples

size.test.mann(.05, .90, .3)

# Should return:
# Sample size per group
#                    44
 

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.