In erhla/cmfproperty: Property Tax Analysis

knitr::opts_chunk$set(
  collapse = TRUE,
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)

This article is a reference section to verify that this package calculates various metrics correctly.

calc_iaao_stats

Coefficient of Dispersion (COD)

$$100 * \frac{\sum_{i=1}^N(SalesRatio_i - SalesRatio_{Median})}{N * SalesRatio_{Median}}$$

Price-Related Differential (PRD)

$$\frac{\frac{\sum_{n=1}^NSalesRatio_i}{N}} {\frac{\sum_{n=1}^N(SalesRatio_i*SalePrice_i)}{N}}$$

Coefficient of Price-Related Bias (PRB)

Arms-Length Measure

$$Percentile_{25}(SalesRatio) - (1.5 * IQR(SalesRatio)) < SalesRatio_i < Percentile_{75}(SalesRatio) + (1.5 * IQR(SalesRatio)) $$

regression_tests (from Hodge 2017)

Paglin

$$ AssessedValue = \alpha_0 + \alpha_1SalesPrice + \epsilon $$

Cheng

$$ ln(AssessedValue) = \alpha_0 + \alpha_1ln(SalesPrice) + \epsilon $$

IAAO

$$ AssessedRatio = \alpha_0 + \alpha_1SalesPrice + \epsilon $$

Kochin

$$ ln(SalesPrice) = \alpha_0 + \alpha_1ln(Assessed Value) + \epsilon $$

Bell

$$ AssessedValue = \alpha_0 + \alpha_1SP + \alpha_2SP^2 + \epsilon$$

Sunderman

$$ AssessedValue = \alpha_{00} + \alpha_{10}SalesPrice + \alpha_{01}Low + \alpha_{02}High + \alpha_{11}LowSalesPrice + \alpha_{12}HighSalesPrice + \epsilon $$

erhla/cmfproperty documentation built on July 21, 2024, 2:24 p.m.