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statpsych (version 1.7.0)

size.supinf.prop2: Sample size for a 2-group superiority or inferiority test of proportions

Description

Computes the sample size in each group (assuming equal sample sizes) required to perform a superiority or inferiority test for the difference in population proportions with desired power in a 2-group design. For a superiority test, specify the upper limit (h) for the range of practical equivalence and specify values of p1 and p2 such that p1 - p2 > h. For an inferiority test, specify the lower limit (-h) for the range of practical equivalence and specify values of p1 and p2 such that p1 - p2 > -h. This function sets the effect size equal to p1 - p2.

Usage

size.supinf.prop2(alpha, pow, p1, p2, h)

Value

Returns the required sample size for each group

Arguments

alpha

alpha level for hypothesis test

pow

desired power

p1

planning value of proportion for group 1

p2

planning value of proportion for group 2

h

lower or upper limit for range of practical equivalence

Examples

Run this code
size.supinf.prop2(.05, .9, .35, .20, .05)

# Should return:
# Sample size per group
#                   408


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