size.test.lc.prop.bs {statpsych}

Sample size for a test of between-subjects proportion linear contrast

Description

Computes the sample size in each group (assuming equal sample sizes) required to test a linear contrast of population proportions with desired power in a between-subjects design. This function requires planning values for all proportions. Set the proportion planning values to .5 for a conservatively large sample size. The planning value for the effect size (linear contrast of proportions) could be set equal to the linear contrast of proportion planning values or it could be set equal to a minimally interesting effect size.

Usage

size.test.lc.prop.bs(alpha, pow, p, es, v)

Arguments

alpha

alpha level for hypothesis test

pow

desired power

p

vector of proportion planning values

es

planning value of proportion linear contrast

v

vector of between-subjects contrast coefficients

Value

Returns the required sample size for each group

Examples

p <- c(.25, .30, .50, .50)
v <- c(.5, .5, -.5, -.5)
size.test.lc.prop.bs(.05, .9, p, .15, v)

# Should return:
# Sample size per group
#                   105