Our paper is designed to accommodate two-dimensional charts, or at best 3 dimensional charts. But those charts are produced at the expense of understandability and appearance of them. What if you want to produce so many to them to accommodate cross-tabbed data?
There are a lot of resources available for modeling on internet, available from books to tutorial to boot-camp trainings; this one focuses more on the concept of modeling rather then discussing details of any particular field.
When we are developing a model or trying to test some formula, we need data and when we don’t have one, we have to create it to suit our needs. This is frequently called dummy data.