How is uniformity measured according to IAAO standards?

Uniformity in property assessments refers to the degree to which properties are assessed at similar values compared to their market value. According to IAAO standards, uniformity is measured using the Coefficient of Dispersion (COD). The COD provides insight into the variability of assessment ratios within a group of properties, highlighting how consistently properties are assessed in relation to their market value.

A lower COD indicates a higher level of uniformity, showing that assessments are closely clustered around the median ratio. Conversely, a higher COD suggests greater disparity in the assessment ratios, indicating potential issues with uniformity. This measure is particularly useful because it directly relates to the fairness and equity of property assessments in a jurisdiction.

Other methods of measuring uniformity, while valuable in their own contexts, do not specifically focus on the assessment parity across a range of properties as effectively as the COD does. For instance, the Coefficient of Variation measures relative variability but does not specifically target how evenly assessments align with actual market values. The Price Ratio and Standard Deviation also provide important data, but they do not directly convey the uniformity in assessments as succinctly as the Coefficient of Dispersion.