Sample size requirements for interval estimation of the kappa statistic for interobserver agreement studies with a binary outcome and multiple raters.

Sample size requirements that achieve a prespecified expected lower limit for a confidence interval about the intraclass kappa statistic are supplied for the case of multiple raters and a binary outcome variable. The expected lower confidence limit achievable for a given number of subjects and raters is also presented. These results should be useful in the planning stages of an interobserver agreement study in which the focus is on interval estimation rather than hypothesis-testing.