The study of social stratification and inequality relies heavily on the analysis of data to adjudicate competing claims. This chapter presents useful skills for designing, conducting, and evaluating social-science research, including research on inequality that is useful when reading subsequent chapters and evaluating evidence related to inequality outside of this course. The first part of the chapter outlines the steps involved in research design, including what makes an effective question for the social sciences and how to plan a study to answer those questions. The second part introduces statistical methods for describing quantitative (or numerical) data, using them to make generalizations and drawing on them to support arguments and hypotheses. In this part of the chapter, students learn sampling basics as well as measures of central tendency, variation, and skew. They also learn about social inference, which is the process of making inferences from the data to larger groups or populations. These skills enable students to design and conduct their own research, but they also are useful in evaluating conclusions made in published research papers and books. This chapter and its exercises focus on evaluating evidence related to social stratification and inequality, but the skills are general and useful beyond the study of stratification.

It may seem unusual to include information on research design and statistics in a book about social stratification and inequality. However, the techniques covered herein are fundamental to making informed judgments about the tremendous volume of quantitative evidence related to inequality. Increasingly, published research and even discussions in the popular press use statistical evidence to support inequality-related arguments. In the past, studies of inequality did not rely on quantitative data and statistical analyses; however, these are becoming less common because high-quality data are readily available and statistical techniques are better able to analyze data. To be a competent consumer of this evidence, it is helpful to understand the basic techniques used to collect and analyze the data. In fact, with the basic skills introduced in this chapter, students will be able to make educated assessments of all of the information discussed in the remainder of this textbook, as well as most of the information encountered elsewhere (e.g., the media).