In recent months I've been hard at work on a new book called Xcelsius 2008 Dashboard Best Practices, to be published by Business Objects Press. I owe my readers a sneak peek of what's to come.
Some ideas are so deceptively simple that they can elude us.
The BubbleMap is one of these. In a nutshell, here's the idea: overlay a bubble
chart on top of a map. What can you do with it? That's what this article is
about.
Overview
Both Excel and Xcelsius have Bubble Charts. These are
similar to X-Y Scatter Charts, but rather than plotting a point of data as a
point, a circle is displayed centered about an X-Y coordinate. The radius of
this circle corresponds to the value in a data series. The radius or circle
size can signify anything we want, be it sales trends, risk metrics, whatever.
The appearance of a group of circles in a chart can
sometimes look like "bubbles", hence a Bubble Chart. Most of the time
bubble charts are associated with displaying data on an X-Y grid (see Figure
1).
Figure 1: Bubble Chart on an X-Y grid
The gridlines in the chart helps to interpret information,
especially when it is quantitative and complex. But sometimes, those horizontal
and vertical lines create visual clutter. It may be simpler to do away with
chart gridlines, and even the background; just place the chart on top of a
picture.
It may be simpler to do away with
chart gridlines, and even the background; just place the chart on top of a
picture.
Of course, the positional arrangement of the bubbles needs to be
appropriate to the underlying image.
It may be simpler to do away with
chart gridlines, and even the background; just place the chart on top of a
picture. 
