US Patent 7765125 Trunk branch repeated transaction index for property valuation

A repeated transaction index (RTI) for estimation of a home price index (HPI) that controls for systematic bias. Purchase transaction records are used to estimate an HPI for areas large enough to have sufficient transaction data. Bias is removed from non-purchase transaction records using the HPI. All available data is used to estimate a localized HPI that pertains to smaller geographical areas (e.g., zip codes, neighborhoods, etc.) after correction of the biases in the non-purchase transaction records.