CALCULATING DESCRIPTIVE STATISTICS: MEASURES OF VARIATION
Determining the dispersion of the data
Chapter 2 investigated the central tendency, a descriptive statistic used to characterize a collection of data based upon a value (the mean, median, or mode) that was representative of the data set as a whole. In this chapter, you will explore a different category of descriptive statistic, called the variance, that describes how closely spaced—or spread out—the data values are.
When you summarize data using a single number, you lose important information about that data. There’s no law that says you can only use one kind of descriptive statistic to characterize a data set, and in this chapter you’ll learn a few more (including range, standard ...