ci.prop2: Confidence interval for a 2-group proportion difference

In statpsych: Statistical Methods for Psychologists

Confidence interval for a 2-group proportion difference

Description

Computes an adjusted Wald confidence interval for a population proportion difference in a 2-group design.

For more details, see Section 2.2 of Bonett (2021, Volume 3)

Usage

ci.prop2(alpha, f1, f2, n1, n2)

Arguments

alpha	alpha level for 1-alpha confidence
f1	number of participants in group 1 who have the attribute
f2	number of participants in group 2 who have the attribute
n1	sample size for group 1
n2	sample size for group 2

Value

Returns a 1-row matrix. The columns are:

• Estimate - adjusted estimate of proportion difference

• SE - adjusted standard error

• LL - lower limit of the adjusted Wald confidence interval

• UL - upper limit of the adjusted Wald confidence interval

References

\insertRef

Agresti2000statpsych

\insertRef

Bonett2021statpsych

Examples

ci.prop2(.05, 57, 15, 100, 100)

# Should return:
#   Estimate         SE        LL        UL
#  0.4117647 0.06083948 0.2925215 0.5310079

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