1) The data is grouped by zip codes, not by neighborhood (notice that "pacific heights" spans multiple zip codes.) Better would be to have data derived from nei

1) The data is grouped by zip codes, not by neighborhood (notice that "pacific heights" spans multiple zip codes.) Better would be to have data derived from neighborhood polygons that delineate clear neighborhood boundaries 2) The prices are from listing prices (homes for sale), which could obviously vary from zip code to zip code and 3) You're relying on the accuracy of Trulia's data, which... well I won't get into that.