I have modeled counts of health factors at the census tract level geography. When I plot these counts against each other (example: smoking vs. heavy drinking) I get a weird scatterplot output. The results seem to be bi-linear or dovetailing, with one point cloud on a steeper trajectory than the other (see image).
I can't seem to find the right description/definition of this to explore it further. My thought is that one group of census tracts has a steeper correlation and then due to another factor (likely SES or race/ethnicity) there is another lesser correlation.
Does anybody have any information on the shape or pattern of this scatterplot?