The Secret Sauce: How Philadelphia’s 600 nested Geographic Market Areas blend human judgment and Augmented Intelligence
Presentation Category
Modeling and Valuation
General Session Description
As we all know, in our industry, it’s all about location, location and location. Philadelphia’s Geographic Market Areas (GMAs) exemplify what we call Augmented Intelligence—the fusion of human expertise and analytical systems to map how real markets behave. Rather than relying on automated clustering or static neighborhood definitions, Philadelphia’s GMAs are built through iterative collaboration between the Mass Appraisal (Modeling) team, Property Evaluators, GIS dept, and management, supported by regression feedback, data analysis, and geo-visual dashboards. Emerging from the informed judgment of evaluators, supervisors, and administrators, these market areas formalize decades of local expertise into a structured, data-driven geography—bridging human insight with analytical precision. And this is a feature, not a bug, in our process: by design, human judgment remains central, ensuring that data serves experience rather than replacing it. The result is a living and nested spatial hierarchy: Zone, Group, Area, and GMA, that achieves both precision and scalability across more than 600 residential single-family market areas. Far more than a boundary system, GMAs represent Philadelphia’s “secret sauce” for mass appraisal modeling—a fine-grained, adaptable, nested geography continuously refined through visualization, diagnostics, and cross-department collaboration. Every three to four years, dashboard-driven reviews ensure that GMAs evolve with shifting markets and urban change. This synergy of data and judgment transforms traditional neighborhood-based modeling into a more dynamic framework. The process also helps assessors and constituents buy-in to the resulting neighborhood definitions By pairing human insight with data science, Philadelphia has created a scalable template for spatially intelligent, market-aligned assessments.
Start Date
3-31-2026 10:30 AM
End Date
3-31-2026 12:00 PM
The Secret Sauce: How Philadelphia’s 600 nested Geographic Market Areas blend human judgment and Augmented Intelligence
As we all know, in our industry, it’s all about location, location and location. Philadelphia’s Geographic Market Areas (GMAs) exemplify what we call Augmented Intelligence—the fusion of human expertise and analytical systems to map how real markets behave. Rather than relying on automated clustering or static neighborhood definitions, Philadelphia’s GMAs are built through iterative collaboration between the Mass Appraisal (Modeling) team, Property Evaluators, GIS dept, and management, supported by regression feedback, data analysis, and geo-visual dashboards. Emerging from the informed judgment of evaluators, supervisors, and administrators, these market areas formalize decades of local expertise into a structured, data-driven geography—bridging human insight with analytical precision. And this is a feature, not a bug, in our process: by design, human judgment remains central, ensuring that data serves experience rather than replacing it. The result is a living and nested spatial hierarchy: Zone, Group, Area, and GMA, that achieves both precision and scalability across more than 600 residential single-family market areas. Far more than a boundary system, GMAs represent Philadelphia’s “secret sauce” for mass appraisal modeling—a fine-grained, adaptable, nested geography continuously refined through visualization, diagnostics, and cross-department collaboration. Every three to four years, dashboard-driven reviews ensure that GMAs evolve with shifting markets and urban change. This synergy of data and judgment transforms traditional neighborhood-based modeling into a more dynamic framework. The process also helps assessors and constituents buy-in to the resulting neighborhood definitions By pairing human insight with data science, Philadelphia has created a scalable template for spatially intelligent, market-aligned assessments.