Isarithmic Maps of Public Opinion Data
By David B. Sparks
Sparks uses isarithmic maps – which are essentially topographic or contour maps, wherein a third variable is represented in two dimensions by color, or by contour lines, indicating gradations – to represent various public opinion data. The map is produced from over 30,000 individual responses to the standard 7-point party identification question. Sparks generated dense grid of points across the map, and calculated a distance-weighted mean value for each point, as well as a distance-weighted response density for each point.
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