Session 2: Mass Appraisal Model Building (Basic)

Mass Appraisal Model Building: Constructing the First BLUE-Ready Model (Session 2 / Basic)

Whether you are launching a valuation start-up, modernizing CAMA systems, or learning mass appraisal for the first time, high-performance AVMs aren't built on black-box algorithms—they are built on methodological discipline.

In Session 2, we transition from raw sampling to active Model Building, executing our uniform OLS Pipeline on a verified baseline dataset of 6,699 single-family sales.

Key Highlights from Session 2:

·        Administrative Data Governance: How to resolve structural multicollinearity by consolidating redundant land-use and PUD categories into clean binary indicators.

·        Endogenous Time Indexing: Capturing market appreciation directly from sale data using a continuous MONTHS SINCE temporal term—avoiding rigid pre-indexed assumptions.

·        The Power of Two-Pass Regression: See how auditing standardized residuals (|Z| > 2.00) and pruning just 4.5% of unrepresentative market noise radically transforms model diagnostics:

o   Explanatory Power (R^2): Bounded from 65.5% up to 81.5%.

o   Precision (SEE): Compressed error dispersion by 37.9% (from $62,154 down to $38,612).

o   Residual Normality: Collapsed excess Kurtosis from a heavy-tailed 9.6270 down to 0.1676, achieving true Best Linear Unbiased Estimator (BLUE) status.

We’ve made the Executive Summary and Methodology Blueprint free for everyone on Substack and Patreon! Paid subscribers get the full code, matrix specifications, and pre- and post-outlier sales ratio distribution analyses.

Read the full session here: https://www.patreon.com/SidSom/posts/basic-mass-model-171049002

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