Bubble Charts

Standard bubble charts display three dimensions, X, Y, and bubble variable. Aabel allows displaying values of a 4^rd variable on a bubble chart using a color-scale:

One of the chart types that can be used for creating a thematic group overlay, is the bubble chart. For this purpose, the bubble chart X and Y are being coordinates (easting-northing or longitude-latitude), and Z representing values of a data theme. When creating a thematic group, the X-Y coordinates of the chart and the base map polygons must have the same projection system and data units. If your data require transformation, you can use the map projection utilities built into Aabel worksheets.

The image below displays a thematic group overlay, that is a thematic map is combined with a bubble chart using square-shaped bubble markers; here, the color-coded markers show the highest 1-hour ambient ozone concentration (in ppm) measured at each monitor during 2006 (source of data: The Environmental Protection Agency's AIRS.

Here, the values of the 3^rd, 4^th, and 5^th variables are represented using the bubble size, a color-scale, and value labels, respectively.

For readability purposes, displaying a 5^th dimension as value labels on a bubble chart is only suitable for very small data sets.

In a standard bubble chart, Aabel allow values of the bubble variable to be displayed either by the size of bubble markers (see the left-hand side image below) or a color scale (see the right-hand side image below).