Wealthy households as a percentage of all households. Mean allocation = total amount / total individuals. Example: gross domestic product per capita (total GDP / total population) Rate of change = total at later time / total at earlier time. Example: annual population growth rate. These are not equivalent, nor is one better than another. Rather, they tell different aspects of a geographic narrative. For example, a choropleth map of the population density of the Latino population in Texas visualizes a narrative about the spatial clustering and distribution of that group, while a map of the percent Latino visualizes a narrative of composition and predominance.Failure to employ a proper normalization will lead to an inappropriate and potentially misleading map. Classification Every choropleth map has a strategy for mapping values to colors. A classified choropleth map separates the range of values into classes, with all of the districts in each class being assigned the same color. An unclassed map (sometimes called n-class) directly assigns a color proportional to the value of each district. Starting with Dupin's 1826 map, classified choropleth maps have been far more common. It is likely that this was originally due to the greater simplicity of applying a limited set of tints; only in the age of computerized cartography have unclassed choropleth maps even been feasible, and until recently, they were still not easy to create in most mapping software. Waldo R. Tobler, in formally introducing the unclassed scheme in 1973, asserted that it was a more accurate depiction of the original data, and stated that the primary argument in favor of classification, that it is more readable, needed to be tested. The debate and experiments that followed came to the general conclusion that the primary advantage of unclassed choropleth maps, in addition to Tobler's assertion of raw accuracy, was that they allowed readers to see subtle variations in the variable, without leading them to believe that the districts the fell into the same class had identical values. Thus, they are able to better see the general patterns in the geographic phenomenon, but not the specific values. The primary argument in favor of classed choropleth maps is that it is easier for readers to process, due to the fewer number of distinct shades to recognize, which reduces cognitive load and allows them to precisely match the colors in the map to the values listed in the legend. Classification