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

In statpsych: Statistical Methods for Psychologists

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.

For more details, see Section 2.23 of Bonett (2021, Volume 3)

Usage

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

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

Value

Returns the required sample size for each group

References

\insertRef

Bonett2021statpsych

Examples

size.supinf.prop2(.05, .9, .35, .20, .05)

# Should return:
# Sample size per group
#                   408

statpsych documentation built on Jan. 13, 2026, 1:07 a.m.