Abstract

Inverse sampling for McNemars test is studied. Sampling is conducted until a pre-specified number of discordant pairs is observed instead of sampling until a pre-specified total number of pairs is observed. The joint likelihood is decomposed into a product of a negative binomial distribution for the number of pairs required to observe r discordant pairs, a binomial distribution for the number of successes in the concordant observations, and a binomial distribution for the number of successes in the discordant observations. Since inference in this problem is based on the discordant observations, inverse sampling controls the type II error when small numbers of discordant observations are observed and the exact binomial test is required. The control results from fixing the sample size for the exact binomial test.  Standard sampling instead lets the sample size for the exact binomial test vary and then performs the test conditionally on the observed number of discordant pairs.

This work is licensed under a Creative Commons Attribution 4.0 License.