Be careful with statistics. Spend some quality time in Cambridge in particular and you will soon learn why it's statistical makeup is what it is. Cambridgians are either rich or not.
Also look at how he schools work. Cambridge and Boston for example, have mandatory bussing, so your kids won't go to a neighborhood school.
You should try to use other factors to avoid living in a bad area. For example, penalize areas within 10 blocks of hospitals and large universities. Institutions usually maintain slummy property in the immediate vicinity to make room for expansion.
Also look at property tax rate as a percentage of property value. Higher rate cities that have cheap rent aren't places where you want to live.
The author of the SP is using median income as a proxy to estimate how affordable the housing is to someone like himself. If there are no people at his income living there, then the type of housing he is looking for is not available.
Also look at how he schools work. Cambridge and Boston for example, have mandatory bussing, so your kids won't go to a neighborhood school.
You should try to use other factors to avoid living in a bad area. For example, penalize areas within 10 blocks of hospitals and large universities. Institutions usually maintain slummy property in the immediate vicinity to make room for expansion.
Also look at property tax rate as a percentage of property value. Higher rate cities that have cheap rent aren't places where you want to live.