PrintWhichever approach you have chosen to make voter population surfaces, it is the difference between the votes for each party that will determine the estimated election results; so, at this point, it is necessary to combine the two estimated surfaces in a 'map calculation'.
- Use the Raster Calculator to specify an equation subtracting the estimated Democratic Party voter density from the estimated Republican Party voter density, and run the tool. Call your resulting layer RepMaj plus a suffix that indicates which density surface method you derived the layer from.
You should get an output surface that is positive in some areas (Republican majority) and negative in others (Democratic majority).
NOTE: If you are interested in comparing the results of the three methods, you need to calculate the difference between the votes for each party described above, and the step described on the next page for each of the methods (i.e., three times). The comparison between the three methods is optional.