# A.3.1 Lesson Summary

In statistics, a

**variable**is a characteristic that can take on different values. A**categorical variable**is a variable that takes on values which can be divided into groups or categories. Data from two categorical variables about a single subject can be organized using a**two-way table**. For example, this two-way table shows the results from 170 responses to a survey asking people their age group and whether they have a cell phone or not. The 38 in the table means that 38 of the 170 people surveyed are in both the 13–15 years old age category and have a cell phone. The two-way table also shows that 55 of the people surveyed do not have cell phones, since 35 + 12 + 8 = 55 The categories for a single variable should not overlap (a person cannot be 10–12 years old*and*13–15 years old at the same time); each individual is included in only one of the cells in the table rather than in multiple places.## New Resources

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