Visualizing complex multidimensional data using heat maps

The Heat Map visualization is actually two visualizations in one. At a basic level, it is a simple heat map, which we will get to shortly; at a more advanced level, it is also a dendrogram, or tree-structured graph.

Heat maps

A heat map is very similar in concept to a cross table, or even just a spreadsheet, except instead of numbers, each cell is configured to display a color that reflects an underlying number. It provides a very intuitive representation of the relative values of complex multidimensional data. Compare the following pictures of monthly temperatures for a selection of American states. They are identical, except that one shows the actual temperatures in °C and the other shows a heat map to represent the temperatures. Which visualization do you think conveys the temperature pattern better?

The second visualization is as follows:

Let's look at how to configure a heat map in Spotfire. For this exercise, we're going to use...