Metrics for ranking neighborhoods/cities/towns

[Justin charles Calma]

Hi all! I'm new to these forums but I've read a lot and I keep hearing about A-F neighborhoods. As someone with a background in science classifications intrigue me but also help me streamline strategies. So I was wondering are there any specific metrics you use to rank these neighborhoods i.e. population size/density, income, number of foreclosures, crime rate, ect. or are they more based on "hearsay"? Also where would i find such metrics? I'd like to be able to streamline the process of finding new areas to invest as well as which strategies would work best. Thanks in advanced!