Comparing values

Often, you will want to compare the differences between measured values across different categories. You might find yourself asking the following questions:

• How many customers did each store serve?
• How much energy did each wind farm produce?
• How many patients did each doctor see?

In each case, you are looking to make a comparison (among stores, wind farms, or doctors) in terms of some quantitative measurement (the number of customers, units of electricity, and patients).

Let’s take a look at some examples of visualizations that help answer these types of questions.

Bar charts

Here is a simple bar chart, similar to the one we built in Chapter 1, Taking Off with Tableau:

Figure 3.1: A bar chart showing the number of patient visits by department

This bar chart makes it easy to compare the number of patient visits between various departments in the hospital. As a dimension, Department slices the data according...