Staafdiagram

Recall that qualitative data represent non-numerical variables such as different hair colors, types of vehicles, or various courses offered by a college. 

For instance, consider a frequency table with the number of students enrolled for each of these courses—Statistics, Biology, Physics, and Chemistry.  

Such qualitative data can be represented visually using a bar graph. 

The categories of qualitative data—the different courses offered—are represented along the horizontal axis, and the frequencies, or the number of students, are given along the vertical axis. 

Then, draw bars of equal width connecting the categories and the corresponding number of students. The height of these bars denotes the frequencies of different categories.

The first bar indicates that five students are enrolled in Statistics, the second bar shows three students enrolled in Biology, and so on. These bars can be placed with or without gaps between them.