Chapter 3. Data Visualization

As the name suggests, this chapter describes the various methods commonly used to display data visually. A picture is worth a thousand words and a good graphical display is often the best way to convey the main ideas hidden in the numbers. Dr. Snow's Cholera Map (Figure 1-3) is a classic example.

Here is another famous example, also from the nineteenth century:

Figure 3-1. Minard's map of Napoleon's Russian campaign

This map shows the path of Napoleon and his army during the War of 1812, marching from France to Moscow and back. The main idea being conveyed here is that the size of the army at each point in the campaign is represented by the width of the lines of advance and retreat.