size.ci.ratio.prop2 {statpsych}

Sample size for a 2-group proportion ratio confidence interval

Description

Computes the sample size in each group (assuming equal sample sizes) required to estimate a ratio of proportions with desired confidence interval precision in a 2-group design.

Usage

size.ci.ratio.prop2(alpha, p1, p2, r)

Arguments

alpha

alpha level for 1-alpha confidence

p1

planning value of proportion for group 1

p2

planning value of proportion for group 2

r

desired upper to lower confidence interval endpoint ratio

Value

Returns the required sample size for each group

Examples

size.ci.ratio.prop2(.05, .2, .1, 2)

# Should return:
# Sample size per group
#                   416