Example Numeric Maps
The two maps below present the same source data in the same number of classes (four), but the first is an equal-interval map while the second is equal-number (quantile). The equal-interval scheme divides the numeric range into subranges of equal size; the equal-number scheme places the states into classes of the same size (in this case, four classes with roughly 14 states / territories in each).
Note that the equal-interval map highlights that South Dakota and Ohio are outliers. The decision to use equal-interval vs. equal-number classification depends on the content owner’s public health message regarding the data.
Note regarding tooltips: The top map illustrates the “click” action for tooltips (click a state to see), while the bottom map uses the “hover” action. Using the click option for the top map, we were able to include links for more information in the tooltips.