But I do take back my statement about rainbow spectrums not being a good idea . . . or at least amend it by adding " for choropleth maps " ( ie, maps with predefined area units ), and adding " usually " to " not a good idea ".
22.
In 1829 he published, with Andre-Michel Guerry, " Statistique compar�e de l'�tat de l'instruction et du nombre des crimes dans les divers arrondissements des Acad�mies et des Cours Royales de France ", the first comparative choropleth map showing crime in relation to level of instruction.
23.
:: : : : : Here is a fairly good use of a rainbow spectrum for a choropleth map with many classes ( 10, plus a gray " no data " or " out of range " ) : ( plus it satisfies StuRat's " the sea must be blue ! " criterion ).
24.
A "'choropleth map "'( from Greek ????? ( " area / region " ) + ?????? ( " multitude " ) ) is a thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map, such as population density or per-capita income.
