Forensic Valuation Modeling: Fixing Costly Errors, Bridging Missing Links (Building More Defensible Models and Achieving BLUE Status)

For decades, valuation models used in property assessment have suffered from significant gaps and costly mistakes. This book exposes the most common Missing Links — critical concepts and procedures often overlooked in traditional AVM and CAMA workflows — and tackles the Costly Errors that quietly undermine model accuracy, fairness, and legal defensibility.

Written for independent consultants, appeal attorneys, assessor-turned-modelers, and forward-thinking assessing offices, this practical guide delivers a forensic approach to valuation modeling. Using clear Excel-based methods, readers will learn how to implement proper categorical coding, the 2-Pass Outlier Protocol, rigorous representativeness testing, OLS assumption validation, and the powerful Three-Way Forensic Equity Analysis. This book also strongly emphasizes that adding GIS or spatial variables on-the-fly during the modeling process must be avoided at all costs, as this common shortcut destroys model integrity and prevents achieving BLUE status.

Whether you are building new models, auditing existing assessment rolls, or preparing for appeals and ratio challenges, this book equips you with the tools to close dangerous gaps and eliminate harmful shortcuts. It emphasizes achieving statistical integrity (BLUE status) while maintaining real-world practicality and transparency.

The next generation of valuation professionals must move beyond legacy practices. This book provides the roadmap — bridging traditional mass appraisal with modern forensic techniques to create more accurate, equitable, and defensible valuation models.

By Sid Som, MBA, MIM

Copyright June 2026

ISBN: 9798199627665