N.cohen.kappa {irr}R Documentation

Sample Size Calculation for Cohen's Kappa Statistic

Description

This function is a sample size estimator for the Cohen's Kappa statistic for a binary outcome. Note that any value of "hypokappa" in the interval [0,1] is acceptable (i.e. Kappa=0 is a valid null hypothesis).

Usage

 N.cohen.kappa(rate1, rate2, kappa, hypokappa, power=.8, alpha=.05, twosided=FALSE)

Arguments

rate1 The probability that the first rater will record a positive diagnosis
rate2 The probability that the second rater will record a positive diagnosis
kappa The true Cohen's Kappa statistic
hypokappa The value of kappa under the null hypothesis
alpha Type I error of test
power The desired power to detect the difference between kappa and hypokappa
twosided TRUE if test is two-sided

Value

returns required sample size

Author(s)

Ian Fellows ifellows@ucsd.edu

References

Cantor, A. B. (1996) Sample-size calculation for Cohen's kappa. Psychological Methods, 1, 150-153.

See Also

kappa2

Examples

 # Testing H0: kappa = 0.7 vs. HA: kappa > 0.7 given that
 # kappa = 0.85 and both raters classify 50
 N.cohen.kappa(0.5, 0.5, 0.7, 0.85)

[Package irr version 0.70 Index]