The study also evaluates the level of uniformity in the assessment of real property within and among jurisdictions throughout the Commonwealth as reflected by a standard statistical measure known as the coefficient of dispersion (COD).
The coefficient of dispersion measures how closely the individual ratios are arrayed around the median ratio. The smaller the measure of dispersion, the greater the uniformity of the ratios. The more closely the ratios are grouped around the median, the more equitable was the property assessment, since properties were assessed at similar rates. As market activity decreases or as the complexity of properties increases, the coefficient of dispersion often rises, even though appraisal procedures may be valid. According to the International Association of Assessing Officers “…a coefficient of 10% or less indicates a good distribution of assessments for residential properties. Similarly, a coefficient of 15% or less indicates a good distribution for more diverse classes (of property)…”
This study serves as a component in the basic school aid distribution formula and as an element in the determination of assessment levels of Public Service Corporation property.
The overall median assessment/sales ratios and coefficients taken from the 2017 assessment/sales ratio study for the City of Fairfax and surrounding jurisdictions are as follows:
|City of Fairfax
|City of Falls Church
|City of Manassas||
City of Alexandria
|Prince Wm. County
*Source: Median Assessment/Sales Ratios for Virginia Localities, published May 2018, Virginia Dept. of Taxation.