Neighborhood appreciation rates from NeighborhoodScout are based on both median house value data reported by respondents via the U.S. Bureau of the Census, and a weighted repeat sales index, meaning that they measure average price changes in repeat sales or refinancing’s on the same properties. This information is obtained by reviewing repeat mortgage transactions on single-family properties whose mortgages have been purchased or securitized by Fannie Mae or Freddie Mac (by the FHFA). Then proprietary algorithms developed by NeighborhoodScout are applied to produce neighborhood appreciation rates.