House Price Index Technical Documentation
6. How do I interpret "four-quarter," "one-year," "annual," and "one-quarter" price?
The "four-quarter" percentage change in home values is simply the price change relative to the same quarter one year earlier. For example, if the HPI release is for the second quarter, then the “four-quarter” price change reports the percentage change in values relative to the second quarter of the prior year. It reflects the best estimate for how much the value of a typical property increased over the four-quarter period (FAQ #2 reports the types of properties included in this estimate). "One-year" and "annual" appreciation are used synonymously with "four-quarter" appreciation in the full quarterly HPI releases.
Similar to the "four-quarter" price changes, the "one-quarter" percentage change estimates the percentage change in home values relative to the prior quarter. Please note that, in estimating the quarterly price index, all observations within a given quarter are pooled together; no distinction is made between transactions occurring in different months. As such, the "four-quarter" and "one-quarter" changes compare typical values throughout a quarter against valuations during a prior quarter. The appreciation rates do not compare values at the end of a quarter against values at the end of a prior quarter.