Reference

Functions

Coefficient of Dispersion (COD)

COD is the average absolute percent deviation from the median ratio. It is a measure of horizontal equity in assessment. Horizontal equity means properties with a similar fair market value should be similarly assessed.

cod()   cod_ci()   cod_met()

Price-Related Differential (PRD)

PRD is the mean ratio divided by the mean ratio weighted by sale price. It is a measure of vertical equity in assessment. Vertical equity means that properties at different levels of the income distribution should be similarly assessed.

prd()   prd_ci()   prd_met()

Price-Related Bias (PRB)

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()   prb_ci()   prb_met()

Kakwani Index (KI)

The Kakwani Index (KI) is a Gini-based measure to test for vertical equity. The output is the ordered cumulative distribution of assessed values minus the ordered distribution of sale prices.

ki()

Modified Kakwani Index (MKI)

The Modified Kakwani Index (MKI) is a Gini-based measure to test for vertical equity. The output is the ordered cumulative distribution of assessed values divided by the ordered distribution of sale prices.

mki()   mki_met()

Other functions

Calculate confidence intervals

boot_ci()

Detect sales chasing in sale ratios

is_sales_chased()

Detect outlier values

is_outlier()

Data

Sample data used for testing and demonstrations

ccao_sample() quintos_sample()