2.12:
Bar Graph
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.
2.12:
Bar Graph
A bar graph is also called a bar chart and consists of bars that are separated from each other. It either uses horizontal or vertical bars to show comparisons among categories. The bars can be rectangles, or they can be rectangular boxes (used in three-dimensional plots). One axis of the graph represents the specific categories being compared, and the other axis shows a discrete value. In this graph, the length of the bar for each category is proportional to the number or percent of individuals in each category. Some bar charts show bars clustered in groups of more than one (grouped bar graphs), and others depict the bars divided into subparts to show cumulative effect (stacked bar graphs). A bar graph is a better choice than a line graph or histogram because this data is categorical rather than continuous. Also, it is appropriate to compare the relative size of the categories. It is to be noted that the bar graphs that are organized from highest to lowest are called Pareto charts.