Price-Related Bias (PRB)

assesspy.prb(assessed, sale_price, round=None)

PRB is an index of vertical equity that quantifies the relationship betweem ratios and assessed values as a percentage. In concrete terms, a PRB of 0.02 indicates that, on average, ratios increase by 2% whenever assessed values increase by 100 percent.

PRB is centered around 0 and has a generally accepted value of between -0.05 and 0.05, as defined in the IAAO Standard on Ratio Studies Section 9.2.7. Higher PRB values indicate progressivity in assessment, while negative values indicate regressivity.

Parameters:

• assessed (numeric) – A numeric vector of assessed values. Must be the same length as sale_price.

• sale_price (numeric) – A numeric vector of sale prices. Must be the same length as assessed.

• round (int) – Indicate desired rounding for output.

Returns:

A numeric vector containing the PRB of the input vectors.

Return type:

float

Example:

# Calculate PRB:
import assesspy as ap

ap.prb(ap.ratios_sample().assessed, ap.ratios_sample().sale_price)