Chapter 2: Descriptive Statistics

As indicated in the introduction, we will begin the Exploratory Data Analysis part of the course by exploring (or looking at) one variable at a time.

As we saw in Data Types and Levels of Measurement, the data for each variable are a long list of values (whether numerical or not), and are not very informative in that form. In order to convert these raw data into useful information we need to summarize and then examine the distribution of the variable. By distribution of a variable, we mean:

• what values the variable takes, and
• how often the variable takes those values.

This chapter has two sections. We will first learn how to summarize and examine the distribution of a single categorical variable, and then do the same for a quantitative variable.