J. Wayne Moore
IAAO's Fair and Equitable Article
IAAO's Journal of Property Tax Assessment & Administration Article
Because it is necessary for assessors to prepare value estimates for huge numbers of properties, all at a specific point in time each year, a process called computer assisted mass appraisal (CAMA), which uses Automated Valuation Models (AVMs), has evolved during the past 35 years to handle the logistic challenge presented by the task. Several CAMA methodologies using different AVMs exist for determining the assessed value of residential properties. A large research study and controlled experiment that statistically tested the results of the several CAMA methodologies when applied under the same circumstances has not been reported until now. This research used all valid market sale transactions for the five years of 1999 through 2003 to estimate selling prices of an actual residential property population in an assessing jurisdiction by using four different CAMA methodologies. The model specification, calibration and value estimation work was done blindly by nine independent CAMA practitioners from across North America without knowledge of the source of the data, the actual 2004 sale prices, or even names of other participants. Six of the participants used a generic AVM market model specification approach and were free to select software tools. Three used a pre-specified transportable AVM. Actual sale prices for 2004 valid market transactions for properties from the same population were used to compare the predictive accuracy of each of the CAMA methods to determine if any statistical significance in predictive accuracy existed between the methods. This paper reports the results of the controlled experiment conducted under the supervision of an academic mentor.
Fair and Equitable article reprinted from “Which AVM is Best,” by J. Wayne Moore, 2005, Fair & Equitable, Vol 3, Issue 8, beginning on p. 9. © 2005 by International Association of Assessing Officers (IAAO), Reprinted with permission. The statements made or opinions expressed by authors in Fair & Equitable do not necessarily represent a policy position of the International Association of Assessing Officers.
Reprinted from “Performance Comparison of Automated Valuation Models” by J. Wayne Moore, 2006, Journal of Property Tax Assessment & Administration, Vol 3, Issue 1. © 2006 by International Association of Assessing Officers (IAAO) and International Property Tax Institute (IPTI), Reprinted with permission.