Section 280-RICR-40-00-2.9 - Conducting the Ratio StudyA. The assessment/sales ratio (ASR) and the measure of uniformity better known as the coefficient of dispersion (COD) about the median should be calculated for each class of property for which there are sufficient sales; and should be calculated for the city/town as a whole. The above measure for each city/town should conform to International Association of Assessing Officers (IAAO) standards upon completion of the property valuation update.B. A comparison of each classes' Assessment Sales Ratio and Coefficient of Dispersion with the city/town wide ASR and COD may point out assessment inequities.280 R.I. Code R. 280-RICR-40-00-2.9