Interaction tests for 2 ×s×t contingency tables

Abstract

SUMMARY The interaction test for 2×2×t contingency tables of Zelen (1971) is extended to 2×s×t tables. This test is related to the tests of partial association, or ‘main effect’, of Birch (1965) and Armitage (1966). These tests are frequency analogues of the log-frequency tests considered by Plackett (1962) and Goodman (1964). The various analyses are illustrated and compared in several numerical examples.