ci_prop_diff_wald: Wald Confidence Interval for Difference in Proportions

In cicalc: Calculate Confidence Intervals

Wald Confidence Interval for Difference in Proportions

Description

Calculates the Wald interval by following the usual textbook definition for a difference in proportions confidence interval using the normal approximation.

Usage

ci_prop_diff_wald(x, by, conf.level = 0.95, correct = FALSE, data = NULL)

Arguments

x	(binary/numeric/logical) vector of a binary values, i.e. a logical vector, or numeric with values c(0, 1)
by	(string) A character or factor vector with exactly two unique levels identifying the two groups to compare. Can also be a column name if a data frame provided in the data argument.
conf.level	(⁠scalar numeric⁠) a scalar in (0,1) indicating the confidence level. Default is 0.95
correct	(logical) apply continuity correction.
data	(data.frame) Optional data frame containing the variables specified in x and by.

Details

(\hat{p}_1 - \hat{p}_2) \pm z_{\alpha/2} \sqrt{\frac{\hat{p}_1(1 - \hat{p}_1)}{n_1}+\frac{\hat{p}_2(1 - \hat{p}_2)}{n_2}}

Value

An object containing the following components:

n	Number of responses in each by group
N	Total number in each by group
estimate	The point estimate of the difference in proportions (p_1 - p_2)
conf.low	Lower bound of the confidence interval
conf.high	Upper bound of the confidence interval
conf.level	The confidence level used
method	Type of method used

Examples

responses <- expand(c(9, 3), c(10, 10))
arm <- rep(c("treat", "control"), times = c(10, 10))

# Calculate 95% confidence interval for difference in proportions
ci_prop_diff_wald(x = responses, by = arm)

cicalc documentation built on Aug. 8, 2025, 7 p.m.