These maps were classified more carefully than those created with cruder methods of classification. The top map shows a so-called "natural breaks" method, where the user assigned class breaks where there were large gaps in the data. There is very little difference between this method and the more rigorously mathematical "nested means" method, shown in the lower map. Both of these schemes almost always produce more accurate representations of the phenomenon in the display than the quantile or equal interval methods.
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