...Jeffrey D. Fisher The purpose of this paper is to stimulate thinking as to how we might produce timely and more reliable estimates of changes in the value of portfolios, price indices based on a portfolio of properties, and other aggregate measures of trends in property values. It is argued...

.... The investigation proceeds by exploring two possible criteria through which the reliability of appraisal estimates may be measured. The first involves the percentage error made in price per unit of comparison (UOC), while the second concerns the total valuation error in the appraisal of real property. Results...