A facility for determining a housing index value for a subject geographic region for a subject period in time is described. For each home in a set of homes within the subject geographic region, the facility determines home attribute values; applies a first valuation model and second valuation for the subject geographic region to the home attributes to obtain estimated values of the home at the beginning and end of the subject period, respectively; and determines an appreciation rate for the home on the basis of the estimated values of the home at the beginning and end of the subject period. The facility combines the appreciation rates to obtain an aggregate appreciation rate for the subject period, and combines the aggregate appreciation rate for the period with a housing index value for a prior period to obtain the housing index value for the subject geographic region and subject period.