More often than not, you will want to compare the differences of measured values across different categories. You might find yourself asking questions like this:
How much profit did we generate in each department?
How many views did each web page get?
How many patients did each doctor see?
In each case, you are looking to make a comparison (among departments, websites, or doctors) in terms of some quantitative measurement (profit, number of views, and count of patients).
The following figure is a simple bar chart, similar to the one we built in Chapter 1, Creating Your First Visualizations and Dashboards:
The sum of sales is compared for each category of item sold in the chain of stores. Category is used as a discrete dimension in the view, which defines row headers (because it is discrete) and slices the sum of sales for each category (because it is a dimension). Sales defines an axis (because it is continuous) and is summed (because it...
