pi.prop {statpsych}

Prediction interval for an estimated proportion

Description

Computes approximate prediction interval for the estimated proportion in a future study with a planned sample size of n. The prediction interval uses a proportion estimate from a prior study that had a sample size of n0.

Usage

pi.prop(alpha, prop, n0, n)

Arguments

alpha

alpha value for 1-alpha confidence

prop

estimated proportion from prior study

n0

sample size used to estimate proportion in prior study

n

planned sample size of future study

Value

Returns a prediction interval for an estimated proportion in a future study

Examples

pi.prop(.1, .225, 80, 120)

# Should return:
#         LL       UL
#  0.1390955 0.337095