How do the three National Association of Realtors housing affordability indexes differ?
NAR research economist Kory Bockman explains:
The National Association of Realtors publishes three affordability indexes. They are the composite, fixed, and adjustable. The are identical with the exception of the interest rate used. Each uses a different interest rate, the composite, fixed, and ARM interests rates from U.S. Federal Housing Finance Board.
In Data Buffet, the concept codes are as follows. The NAR publishes the not seasonally adjusted (NSA) indexes, which Moody's Analytics supplements with seasonally adjusted (SA) versions. The composite indexes are available for the nation and the four census regions; the FRM and ARM indexes are available for the nation only.
||NAR Housing Affordability Index, (Index)
||Using FHFA composite interest rate
||U.S., 4 regions
||Using FHFA fixed-rate mortgage (FRM) interest rate
||Using FHFA adjustable-rate mortgage (ARM) interest rate
The FHFA (formerly FHFB) interest rates derive from the "Terms on Conventional Home Mortgages" monthly dataset, also available on Data Buffet.
Moody's Analytics estimates a quarterly affordability index (RHXAFFQ) for all states, MSAs and metro divisions, based in part on NAR data.
NAR Affordability (Quarterly)