The Analytical Foundations of Adjustment Grid Methods

Within the market data approach to real estate appraisal, two basic types of analysis generally are used: (1) regression analysis; and (2) adjustment grid methods. The focus of this paper is on the adjustment grid methods. Three such methods are identified in the appraisal literature, but their analytical foundations are not clearly presented. The primary objective of this paper is to clarify the analytical foundations of each method. In addition, various ways to estimate the adjustment factors needed to apply the grid methods and a weighting scheme for reconciliation of indicated values are presented. Also, the possible advantage of grid‐based over purely regression‐based predictions is identified.