Appraisal Ratio – The ratio of an individual property’s appraised value shown on the appraisal roll to its market value.
Appraisal Roll Value – The property value estimated by the local appraisal district.
Coefficient of Dispersion (COD) – Measures how tightly or loosely the individual sample ratios are clustered around the median. The lower the COD, the more ratios are found close to the median.
Confidence Interval – Measure of the reliability of the Comptroller’s estimate of school district value; the correct value is assumed to be within this computed range of values.
Grace Period – A two-year period when local appraisal roll value is used to estimate the total taxable value in an eligible school district even though the local appraisal roll values are invalid.
Invalid Value – Local values outside the margin of error.
Local Value – The local estimate of the total taxable value in a school district.
Margin of Error – An acceptable range of values within a school district: one-half of confidence interval (expressed as a percentage) = margin of error.
Market Value – The price for which a property would sell under normal conditions.
Median Level of Appraisal – Measure of accuracy of appraisal district’s appraisals in relation to the standard of 100 percent of market value.
Outliers – Properties with abnormally high or low ratios; can distort ratio studies.
Price-Related Differential (PRD) – Measure of inequity that may arise from systematic differences in the appraisal of low-value and high-value properties. Only an indicator—cannot alone prove vertical equity or inequity.
Sales Chasing – Practice of using the sale of a property to trigger a change in appraised value of that property to (or near) the property’s selling price.
State Value – The total taxable value in a school district.
Stratify – Placing similar properties into groups based on use or value.
Valid Value – Local values inside the margin of error.
Weighted Mean Appraisal Ratio – An average that gives more weight to the ratios of higher valued properties in a sample.