Categorical Data

Abstract

In many experiments and almost all surveys, many, if not all, of the results fall into categories rather than being measurable on a continuous or ordinal scale: e.g., male vs. female, black vs. Hispanic vs. Asian vs. white, in favor vs. against vs. undecided. The corresponding hypotheses concern proportions: “Blacks are as likely to be Democrats as they are to be Republicans.” Or, “the dominant genotype ‘spotted shell’ occurs with three times the frequency of the recessive.” In this chapter, you’ll learn to test hypotheses like these that concern categorical and ordinal data.