Transformations of maps to investigate clusters of disease.

An approach is presented to display and analyze epidemiologic data using population density equalized maps (cartograms). The algorithm for generating these maps is discussed. A specific method for statistically analyzing plotted data is given, followed by an application of maps and analysis to 73 sets of age-, race-, sex-, and site-specific cancer incidence data. The data were obtained from the Surveillance, Epidemiology and End Results project for San Francisco City/County (1978-1981) and combined with 1980 U.S. Census data.