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.
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.