Detecting answer copying when the regular response process follows a known response model

摘要

The test is based on the exact null distribution of the random matches between two test takers under the assumption that the response process follows a known response model.- The null distribution can be generalized to the family of distributions of the number of random matches under the alternative hypothesis of answer copying. The paper shows how this information can be used to calculate such features as the maximum, minimum and expected values of the power function of the test. For the case of the nominal response model, the test is an alternative to the one based on the statistic omega. The differences between the tests are discussed and illustrated using numerical examples.