This document describes the guidelines that were followed (in the main study) when drawing maps of geographic clusters of states with the highest cancer incidence and mortality rates in the United States.
As a starting point, the cluster definition was followed.
Only states that were part of a cluster were drawn on the map. States that were part of the list of states with highest rates, but were not part of a cluster (as per the definition of a cluster), were not drawn on the map, but were specified in the table below the map.
Generally, the goal was to divide the states into three groups/colors as follows:
- Red color - The five states with highest rates (1-5 in the list)
- Purple color - The next five states in the list of highest rates (6-10 in the list)
- Green color - The remaining states in the list (usually 11-15, but could be, for example, 11-17)
In some cases, due to identical incidence or mortality rates between states, states were moved to a different group than specified above.
Here are two examples:
Example 1: If the 5th and 6th states had the same rate, the 5th state was generally colored purple (rather than red), unless the situation described in "example 2" below happened; similarly, if the 10th and 11th states had the same rate, the 10th state was generally colored green (rather than purple).
Example 2: If the 4th, 5th and 6th states had the same rate, the 6th state was colored red (rather than purple); similarly, if the 9th, 10th and 11th states had the same rate, the 11th state was colored purple (rather than green).
To make a general rule of the examples above, if states across a diving line in the list (i.e. 5th/6th and 10th/11th) had identical rates, states were moved to the group that had more states of that rate (second example above). If the same number of states across a diving line had identical rates, the states in the higher group were moved to the lower group (first example above).
Note: The colored maps of US states were created using an online tool.