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

In statpsych: Statistical Methods for Psychologists

Confidence interval for a 2-group proportion difference using inverse sampling

Description

Computes an approximate confidence interval for a population proportion difference when inverse sampling has been used. An approximate standard error is recovered from the confidence interval. With inverse sampling, the number of participants who have the attribute within group 1 (f1) and group 2 (f2) are predetermined, and sampling continues within each group until f1 and f2 attain their prespecified values. With inverse sampling, the sample sizes (n1 and n2) will not be known in advance.

Usage

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

Arguments

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

Value

Returns a 1-row matrix. The columns are:

• Estimate - estimate of proportion difference

• SE - recovered standard error

• LL - lower limit of confidence interval

• UL - upper limit of confidence interval

References

\insertRef

Zou2010statpsych

Examples

ci.prop2.inv(.05, 10, 10, 48, 213)

# Should return:
#  Estimate         SE         LL        UL
#  0.161385 0.05997618 0.05288277 0.2879851

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.