Bar Charts and Dot Charts

Representing category counts as bars and dots

Bar charts are a reasonable way to represent the total counts in a category, as in Figure 1 which shows the number of passengers on the Titanic, by class.

Figure 1: Bar chart of number of passengers on the Titanic, by class

1 Dot Chart

Dot charts represent all the same information as Bar Charts, with less ink. (Here, the axes have been reversed, which can improve readability of the category labels.)

Figure 2: Dot chart of number of passengers on the Titanic, by class

2 Stacked Bar Chart

To see the counts of passengers who were in each class, conditioned on sex, we can use a stacked bar chart. This places each category on the same bar.

Figure 3: Stacked bar chart of number of passengers on the Titanic, by class

Such a representation is quite concise. We can see the difference between the main comparison (by sex), but also the different distribution of classes in each sex.

3 Proportional Stacked Bar Chart

In Figure 3 the y-axis is the total count of passengers. Sometimes it is easier to make appropriate comparisons if we instead plot proportions in each category.

Figure 4: Stacked bar chart of number of passengers on the Titanic, by class