RAPID ANALYSIS OF 2x2 TABLES

Given a 2 by 2 contingency table with marginal totals, one may rapidly determine whether Chi Square is significant at .1, .05, .02, & .01 probability levels for the 2-tailed test by making only 2 entries in charts provided in the text. The chart gives a critical number which, if ~, the f in one of the cells, indicates a signif association. The charts are suitable only for cases where the marginal P lies within the range .1 & .9, & a numerator, the range of 5-49, inclusive. The charts also provide critical values for one-tailed tests for probability levels .05, .025, .01, &.005. Only one entry is required to determine whether a signif association exists. Cases of borderline signif should be computed by the usual exact test. The mathematical justification for the charts is presented: briefly, the probability of a f in a cell, given the total for that line, is distributed binomially. A. L. Ferriss.