Bar charts, introduced in William Playfair’s The Commercial and Political Atlas in 1786, have withstood the test of time for more than two centuries and are still an essential option for any visual analytics project today. In fact, the simple bar chart is the first chart type I try anytime I need to compare numerical values in categorical, or discrete, data. Bar charts are so effective because they leverage the preattentive attribute of height (when the chart is in a vertical orientation) or length (when the chart is in a horizontal orientation).
Note
Preattentive attributes are aspects of a visual that our visual processing system recognizes and is drawn to before slowing down for further, postattentive processing. Preattentive attributes such as height and length—not to mention others like color, size, and position—are processed extremely efficiently by the viewer, making them an ideal mechanism for communicating data.
Creating a Bar Chart
Bar charts are so pervasive and useful that they are the default chart type Tableau creates when you double-click a measure from within the Data pane, which is the first method for creating a bar chart in Tableau. In Figure 7-1, I have simply double-clicked the Profit measure from the Sample – Superstore dataset. The default behavior is for Tableau to place this measure on the Rows shelf with a mark type of Bar, creating a bar chart in a vertical orientation.
Figure 7-1. The default bar chart in Tableau, ...
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