A bar chart is a graph that you can use to compare bar heights of category measures. Bar charts can be made of category tallies, of different statistics by categories, or of summary values. The height of the bars signifies the magnitude of the values. For example, bars could represent:
Total sales for four branch stores for a year
Mean diameters of parts manufactured by four different machines in a factory during a week
Counts of visitors to four local tourist destinations during a weekend
Clustered and stacked bars
You can represent subcategories on bar charts by creating clusters of bars or by stacking bars. For example, suppose you want to track the number of students at four regional high schools by grade.
Creating clusters is helpful when you want to compare subcategories within and across categories. For example, the previous graph shows:
East High has the most students.
Within East High, 12th grade has the most students.
For each high school, the number of students in each grade is similar.
The fewest students are in 9th grade at West High, followed closely by the other three grades at that high school.
Stacking bars is helpful when you want to compare subcategories within categories and categories with each other.