2.1. Introduction

The 2 × 2 contingency table is one of the most common ways to summarize categorical data. Categorizing patients by their favorable or unfavorable response to two different drugs, asking health survey participants whether they have regular physicians and regular dentists, and asking residents of two cities whether they desire more environmental regulations all result in data that can be summarized in a 2 × 2 table.

Generally, interest lies in whether there is an association between the row variable and the column variable that produce the table; sometimes there is further interest in describing the strength of that association. The data can arise from several different sampling frameworks, and the interpretation of the hypothesis ...

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