Chapter 4 introduces inference in the setting of categorical data. We use these methods to answer questions like the following:
What proportion of the public approves of the job the Government is doing?
A Research Enter conducted a poll about support for the equal marriage law, and they used two forms of the survey question. Each respondent was randomly given one of the two questions. What is the difference in the support for respondents under the two question orderings?
We will find that the methods we learned in previous chapters are very useful in these settings. For example, sample proportions are well characterized by a nearly normal distribution when certain conditions are satisfied, making it possible to employ the usual confidence interval and hypothesis testing tools.