Author(s): William M. Doerner, and Wenzhen Lin
Abstract: House price seasonality has been increasing over the last decade, but adjustments have remained largely unchanged in commonly used public data. This paper shows how seasonal adjustments work—both theoretically and applied to observed transactions—when constructing house price indices (HPIs). In this paper, we find the seasonality in the housing market is not uniform across geographies. Evidence is provided about where adjustments are more necessary, how often they should be recalculated, and how the weather-related variables, social and industry characteristics impact difference between adjusted and non-adjusted HPI. Using the Federal Housing Finance Agency's (FHFA's) entire suite of public indices, we update adjustments that have been provided by the FHFA and offer new adjustments for over 400 metropolitan areas and other geographies, which haven't been provided before. We find the difference between previous and updated adjusted indices are relatively small, with slight improvement in recent years.
A revised version of this paper has been accepted for publication in an academic journal with open (free) access. Citation: William Doerner, Wenzhen Lin. 2022. "Applying Seasonal Adjustments to Housing Markets." Cityscape, 24(3), 87-122. https://www.huduser.gov/portal/periodicals/cityscape/vol24num3/ch4.pdf