As the tutorial demonstrates, when setting up data for a cross tab, you create at least one data source and one data set, just as you would to prepare data for other report elements. Unlike a table, a list, or a chart, however, you cannot insert a data set field directly in a cross tab.

To set up data for a cross tab, there is one additional step to perform: creating a cube. The data that you insert in a cross tab must come from a cube. As the tutorial also demonstrates, you build a cube using data from a data set. Figure 18‑27 illustrates how the cross tab gets its data.

If you are wondering why there is an additional data entity, the answer is that the cube offers a far more powerful way to store numeric data for fast analysis.