GIS-BASED MASS APPRAISAL MODEL FOR EQUITY AND UNIFORMITY OF RATING ASSESSMENT

Rating is a major source of income for local authorities. The basis of rating is the assessed values of property holdings from which property tax can be charged. The traditional single valuation method contributes to the inconsistency of assessed values because locational factors are not considered objectively. The traditional method is also unable to produce equity and uniformity of the assessment values consistently. The main objective of this study was to develop a mass appraisal model incorporating spatial analysis and geographic information system (GIS) to produce more accurate predictions of property values and, thus, to achieve an overall equity and uniformity of property rating assessment. In order to achieve the objective, Majlis Perbandaran Kulai was chosen as a study area. The study involved 1,500 property holdings transacted between 2004 and 2006 representing 86 housing areas. The variable components for locational factors, namely accessibility, neighborhood and environment were generated using GIS spatial analysis which included buffering, overlaying, and network analysis. The outputs from the analyses consisted of variable components which were derived objectively and they can assist in the process of forming mass appraisal model. Four mass appraisal models were used as alternative choices to the traditional single valuation method. They were ordinary least squares (OLS), spatial hedonic model (SHM), geographically weighted regression (GWR), and kriging. The outcomes of the models showed that the assessed values were statistically significant. The performance of mass appraisal models from equity and uniformity perspectives was measured using ratio study technique. The four models were compared on the basis of their accuracy in terms of equity and uniformity. It was discovered that the spatial hedonic model (SHM) was the best choice followed by the ordinary least square model (OLS) as the second best choice.