## Section 1.2 Summary

**Exploratory data analysis** uses graphs and numerical summaries to describe the variables in a data set and the relations among them.

The **distribution** of a variable tells us what values it takes and how often it takes these values.

**Bar graphs** and **pie charts** display the distributions of categorical variables. These graphs use the counts or percents of the categories.

**Stemplots** and **histograms** display the distributions of quantitative variables. Stemplots separate each observation into a **stem** and a one-digit **leaf**. Histograms plot the **frequencies** (counts) or the percents of equal-width classes of values.