Learning Outcomes
- Read and interpret data from pie charts and bar charts as percents
Two-Way Tables
Categorical data is sometimes categorized by two attributes. For example, students at a college may be categorized by class standing as well as residential status. Each individual belongs to one class standing (freshman, sophomore, junior or senior) and either lives on campus or commutes.
In a two-way table, or contingency table, counts are displayed by rows corresponding to categories for one attribute and by columns corresponding to categories for the other attribute. The intersection of a row and a column is called a cell, and it tells the number of data values with both characteristics.
| Residential | Commuter | Total | |
| Freshman | 650 | 125 | 775 |
| Sophomore | 300 | 100 | 400 |
| Junior | 350 | 325 | 675 |
| Senior | 310 | 340 | 650 |
| Total | 1610 | 890 | 2500 |
The table above tells us there are 125 freshmen that commute, while the other 650 freshmen live on campus. The total for that row, 775, gives the total number of freshmen. Similarly, the total of the column “Residential” tells us that 1610 students live on campus.
Example
What percent of students at the college are seniors who commute?
Example
What percent of juniors live on campus?
