Heat map in the context of Data visualization

A choropleth map (from Ancient Greek χῶρος (khôros) 'area, region' and πλῆθος (plêthos) 'multitude') is a type of statistical thematic map that uses pseudocolor, meaning color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita income.

Choropleth maps provide an easy way to visualize how a variable varies across a geographic area or show the level of variability within a region. A heat map or isarithmic map is similar but uses regions drawn according to the pattern of the variable, rather than the a priori geographic areas of choropleth maps. The choropleth is likely the most common type of thematic map because published statistical data (from government or other sources) is generally aggregated into well-known geographic units, such as countries, states, provinces, and counties, and thus they are relatively easy to create using GIS, spreadsheets, or other software tools.

A center squeeze is a kind of spoiler effect shared by rules like the two-round system, plurality-with-primaries, and ranked choice voting. In a center squeeze, the majority-preferred and socially optimal candidate is eliminated in favor of a more extreme alternative in an early round, while there are still spoilers. Systems with center squeeze are sometimes called centrifugal ("center-fleeing") because they encourage political polarization.

Candidates focused on appealing to a small base of core supporters can "squeeze" broadly-popular candidates trapped between them out of the race, by splitting the first-preference votes needed to survive earlier rounds. This effect was first predicted by social choice theorists in the 1940s and 50s, and has since been documented in various countries using plurality-style electoral systems.