size.supinf.prop.ps {statpsych}

Sample size for a paired-samples superiority or inferiority test of proportions

Description

Computes the sample size required to perform a superiority or inferiority test for the difference in population proportions with desired power in a paired-samples 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 the difference in proportion planning values. Set the phi correlation planning value to the smallest value within a plausible range for a conservatively large sample size.

Usage

size.supinf.prop.ps(alpha, pow, p1, p2, phi, h)

Arguments

alpha

alpha level for hypothesis test

pow

desired power

p1

planning value of proportion for measurement 1

p2

planning value of proportion for measurement 2

phi

planning value of phi correlation

h

lower or upper limit for range of practical equivalence

Value

Returns the required sample size

Examples

size.supinf.prop.ps(.05, .9, .35, .20, .45, .05)

# Should return:
# Sample size
#         227