We discuss data quality and modeling issues inherent in the use of nationwide property data to value environmental amenities. By example of ZTRAX, a U.S.-wide real estate database, we identify challenges and propose guidance for:
- the identification of arms-length sales
- the geo-location of parcels and buildings
- temporal linkages between transaction, assessor, and parcel data
- the identification of property types (e.g., single-family homes, vacant lands, etc.)
- dealing with missing or mismeasured data for standard housing attributes.
We review current practice and show that how researchers address these issues can meaningfully influence research findings.
ZTRAX is a U.S.-wide database of tax assessment and property transaction records that was shared by Zillow, Inc. free of charge with U.S. academic, nonprofit and government researchers between 2016 and Sept 30, 2023. At PLACES, we linked ZTRAX to digital parcel maps and a wide range of social-environmental variables. This allowed us to develop U.S.-wide high-resolution maps of land value, and to support a wide range of hedonic analyses with collaborators around the country.
Prior versions
Working paper (>700 downloads): Nolte et al. (2021) Studying the impacts of environmental amenities and hazards with nationwide property data: best data practices for interpretable and reproducible analyses. SSRN Working Paper
Supporting Information
Note: the above file was generated with the Oct 2019 version of ZTRAX. Do not use it with later versions of ZTRAX without additional scrutiny. In the Oct 2021 version of ZTRAX, datums had already changed considerably – mostly (but not exclusively) towards NAD83/WGS84.