The method of displaying the geographical variability of the disease on maps using different colors, shading, etc. The logic is not new, but the arrival of computers and computer graphics has made it easy to apply and it is now broadly used in descriptive epidemiology, for instance, to display morbidity or mortality information for the area.
The figure shows an instance. Such mapping might comprise relative rates, absolute rates, etc., and often the viewers impression of the geographical variation in the data might vary quite
markedly according to methodology taken in use.