The temporal maps allow the reader to compare the changes in cancer rates over time. In order to make accurate comparisons of these spatially adaptive filter maps some similar properties are needed. Each map uses the same densified grid, which increases the geographic details in urban areas. From the densified grid, rates and filter sizes are computed based on the closest 50 expected cases. Maps from both time periods must use the same spatial filters, which are determined by using the time period with the lowest rate, largest filter size. The final similarity is that of classification and color scheme. Red areas indicate higher rates than expected and blue areas indicate lower rates than expected, given the statewide incidence rate. The higher than expected and lower than expected portions of the state are colored, while no color is shown for areas closer to the state rate.
Data Sources: Cancer incidence data from the State Health Registry of Iowa. 1:100,000 Digital Raster Graphic from the Iowa Geographic Image Map Server hosted by Iowa State University. County borders from the Natural Resources GIS Library hosted by the Iowa Department of Natural Resources and the US Geological Survey.
Created by David Haynes, Kirsten Beyer, Gerard Rushton at the University of Iowa Department of Geography, software by Chetan Tiwari at the University of North Texas, June 2009.