House Price Index Technical Documentation
16. When are the indexes normalized in the downloadable ASCII data?
The ASCII data for metropolitan areas are normalized to the first quarter of 1995. That is, the HPI equals 100 for all MSAs in the first quarter of 1995. States and divisions are normalized to 100 in the first quarter of 1980. The purchase-only indexes are normalized to 100 in the first quarter of 1991. Note that normalization dates do not affect measured appreciation rates.