Once researchers have designed and executed their study, they're left with a dataset. The focus of this chapter is on the usual first component of the data-analytic process: summarizing and exploring a sample of data—in other words, understanding the data that the researcher (or someone else) has collected.

Using several examples we examine two kinds of tools for summarizing data: displays and descriptive statistics. The section on displays draws attention to frequency distributions and histograms, and the section on statistics focuses on measures of central tendency (the mean, median, and mode) and dispersion (the standard deviation and interquartile range). We end with a discussion of the empirical rule.

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