Detecting answer copying using the kappa statistic

A statistical test for detecting answer copying on multiple-choice tests based on Cohen's kappa is proposed. The test is free of any assumptions on the response processes of the examinees suspected of copying and having served as the source, except for the usual assumption that these processes are probabilistic. Because the asymptotic null and alternative distributions of the kappa statistic are derived under the assumption of common marginal probabilities for all items, a recoding of the item alternatives is proposed to approximate this case. The results from a simulation study in this article show that under this recoding, the test approximates its nominal Type I error rates and has promising power functions.