ci.prop: Confidence intervals for a proportion

In statpsych: Statistical Methods for Psychologists

Confidence intervals for a proportion

Description

Computes adjusted Wald (Agresi-Coull), Wilson, and exact confidence intervals for a population proportion. The Wilson confidence interval uses a continuity correction.

For more details, see Section 1.5 of Bonett (2021, Volume 3)

Usage

ci.prop(alpha, f, n)

Arguments

alpha	alpha level for 1-alpha confidence
f	number of participants who have the attribute
n	sample size

Value

Returns a 2-row matrix. The columns of row 1 are:

• Estimate - adjusted estimate of proportion

• SE - standard error of adjusted estimate

• LL - lower limit of the adjusted Wald confidence interval

• UL - upper limit of the adjusted Wald confidence interval

The columns of row 2 are:

• Estimate - ML estimate of proportion

• SE - standard error of ML estimate

• LL - lower limit of the Wilson confidence interval

• UL - upper limit of the Wilson confidence interval

The columns of row 3 are:

• Estimate - ML estimate of proportion

• SE - standard error of ML estimate

• LL - lower limit of the exact confidence interval

• UL - upper limit of the exact confidence interval

References

\insertRef

Bonett2021statpsych

\insertRef

Agresti1998statpsych

Examples

ci.prop(.05, 120, 300)

# Should return:
#                 Estimate         SE        LL        UL
# Adjusted Wald  0.4013158 0.02811287 0.3462156 0.4564160
# Wilson with cc 0.4000000 0.02828427 0.3445577 0.4580464
# Exact          0.4000000 0.02828427 0.3441290 0.4578664

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