N.cohen.kappa {concord} | R Documentation |
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).
N.cohen.kappa(rate1,rate2,kappa,hypokappa,power=.8,alpha=.05,twosided=FALSE)
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 |
returns required sample size
Ian Fellows ifellows@ucsd.edu
Cantor, A. B. (1996) Sample-size calculation for Cohen's kappa. Psychol. Method., 1, 150-153.
# 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)