irr (version 0.70)

N.cohen.kappa: 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

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% of subjects as positive.
 N.cohen.kappa(0.5, 0.5, 0.7, 0.85)