Session 8 of the Mass Appraisal Modeling series is now live.
In one-step CAMA environments, the finished model writes Just Values directly to the roll. There is no later equalization step. Under those conditions, holdout testing is the most important practical validation a modeler can perform.
This session walks through a complete forward (out-of-time)
holdout protocol — sample construction, representativeness checks, pre- and
post-outlier ratio comparison, and Just Value ratio analysis — and shows why
this approach is a stronger test of residual independence than traditional
statistics such as Durbin-Watson.
The Executive
Summary is free for everyone. Paid
subscribers can access the full session.
Whether
you are managing assessment rolls, building AVMs for institutional secondary
markets, or serving as a forensic valuation expert, out-of-time validation is
what separates robust economic engines from fragile curve-fitting exercises.
Read the full session on Substack now:
https://sidsom.substack.com/p/session-8-holdout-testing-validating
(Coming next: Session 9 on comprehensive IAAO Guideline
Tests followed by Session 10 on Model Application to the
Population!)
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