Sample AVM Results for an Index Model
Geographical Error Variance
By State

This figure shows that on two important measures of AVM error variance -- percentage of AVM values falling within 10% of the sales price and percentage of AVMs overvaluing properties by more than 25% -- there is substantial variance between states for a specific index-based AVM. Variance in the fit of this model at the county level within states is also quite striking (not illustrated here). One might note from the graph that the performance of this particular model is relatively stable from one quarter (in yellow) to the next (in green), but some states show some large shifts in fit. Testing AVMs across time, as well as geography, pricing tiers and property types are key components of model reliability and suitability. These graphics were constructed using 165,000 transactions.