Release: House Price Index
As stated by the source, these annual county indexes should be considered developmental. As with the standard FHFA HPIs, revisions to these indexes may reflect the impact of new data or technical adjustments. Indexes are calibrated using appraisal values and sales prices for mortgages bought or guaranteed by Fannie Mae and Freddie Mac. As discussed in the Working Paper 16-01, in cases where sample sizes are small for the county area, an index is either not reported if recording has not started or a missing value is reported with a period (.). Index values always reflect the native county index, i.e. they are not made with data from another area or year.
For tracking and feedback purposes, please cite Working Paper 16-01 when using these data. A suggested form is: Bogin, A., Doerner, W. and Larson, W. (2016). Local House Price Dynamics: New Indices and Stylized Facts. Federal Housing Finance Agency, Working Paper 16-01. The working paper is accessible at http://www.fhfa.gov/papers/wp1601.aspx.
U.S. Federal Housing Finance Agency, All-Transactions House Price Index for Nassau County, NY [ATNHPIUS36059A], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/ATNHPIUS36059A, May 25, 2018.