There are two ways to measure housing affordability developed by Esri’s Data Development Team: the Housing Affordability Index & the Share of Income to Mortgage.
The Housing Affordability Index
The Housing Affordability Index to display which areas are estimated to have the least or most affordable housing. U.S. Counties that are shaded in the darkest red represent areas with the least affordable housing, while areas shaded the darkest gray are the most affordable.
The Share of Income to Mortgage
The Share of Income to Mortgage represents the percentage of median household income dedicated to monthly payments on a home priced at the median value.