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Figure 11 | International Journal of Health Geographics

Figure 11

From: A procedure to characterize geographic distributions of rare disorders in cohorts

Figure 11

A simplified illustration of the Epiunit NHalf areal unit partitioning algorithm with n max = 5. From the top, for a study population of 50 in a rectangular study area, Step 1, a rectangle is drawn around the study area and the first partition bisects the longer axis. Step 2, any unit that contains more than nmax = 5 locations is bisected on its longer axis. If all units created have at least 3 (> 2.5, or one-half of nmax = 5) locations, assess whether either unit contains more than 5 locations. Step 3, bisect the longer axis of any unit containing more than 5 units. Step 4, if a unit has less than 2.5 locations go back and make a partition into two units such that the location count is approximately equal. Repeat steps 3 and 4 recursively until all units have between 3 and 5 locations.

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