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statpsych (version 1.7.0)

size.ci.biphi: Sample size for biserial-phi correlation confidence interval

Description

Computes the sample size required to estimate a biserial-phi correlation with desired confidence interval precision. Set the biserial-phi planning value to the smallest absolute value within a plausible range for a conservatively large sample size. The column variable is assumed to be naturally dichotomous and the row variable is assumed to be artificially dichotomous.

Usage

size.ci.biphi(alpha, p1, p2, cor, w)

Value

Returns the required sample size

Arguments

alpha

alpha level for 1 - alpha confidence

p1

planning value for row 1 marginal proportion

p2

planning value for column 1 marginal proportion

cor

planning value for biserial-phi correlation

w

desired confidence interval width

Examples

Run this code
size.ci.biphi(.05, .2, .5, .3, .4)

# Should return:
#  Sample size
#          195


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