Which component is essential for model calibration in mass appraising?

Model calibration in mass appraising involves fine-tuning a predictive model to ensure it accurately reflects the value of properties based on their characteristics and market conditions. Establishing formulas and coefficients is crucial in this process because it directly affects how the model interprets data and produces value estimates.

When calibrating a model, appraisers adjust the coefficients associated with various property attributes (like size, age, location, etc.) to align the model's output with actual market values. This meticulous adjustment helps in achieving a model that is both reliable and relevant, ensuring the values generated are reflective of real market conditions and trends.

While understanding market trends, collecting public records, and assessing local taxes are important in the broader context of mass appraisal, these activities primarily support the foundational data and context upon which the model operates. They do not involve the mathematical tuning of the model itself, which is where establishing formulas and coefficients plays its critical role.