| 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; sum of PTD value estimates for tested categories. |
| 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 locally appraised value in a school district. |
| Margin of Error | An acceptable range of values within a school district; one-half of confidence interval (expressed in 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 the property’s selling price. |
| State Value | The total taxable value in a school district. |
| Stratify | Placing similar properties into a group based on use or value. |
| Valid Value | Local values inside the margin of error. |
| Value-Stratified Weighted Mean Appraisal | Mechanism to adjust the sample to be representative of the property population from which it is taken; considers value and construction. |
| Weighted Mean Appraisal Ratio | Giving more weight to higher values of individual properties in a sample. |
