The PRD is mean (valuation-to-selling price) ratio divided by the weighted (by selling prices) mean ratio. The PRD assesses the level of uniformity in AVM valuation-to-sales price ratios between low and high values properties. The statistic has a slight bias upward. Price-related differentials above 1.03 tend to indicate assessment regressivity; Price-related differentials below 0.98 tend to indicate assessment progressivity. Used as a measure of AVM precision.