The development of a GIS-based property information system for real estate valuation

Property value is a function of locational, physical, legal and economic factors. The prevalent method of valuation is the comparison technique which involves the analysis of properties similar to the one being valued in order to isolate and quantify individual influences on value. A primary factor that affects real estate value is location (Goodall 1972) yet the quantification of this factor in the valuation process is traditionally accounted for by the valuer`s expert knowledge of a locality. This paper demonstrates that a more quantitative approach to the analysis of spatial property information would enhance the real estate valuer`s understanding of locational influences on property value. To achieve this a GIS-based property valuation database was developed for a study area that permitted the geographical representation of property information at the individual property level. Network analysis was then used to examine the influence of accessibility on property value and value maps were constructed to illustrate the resultant geographical spread of property values. It is suggested that this aids the valuer in the selection of comparable evidence based on locational criteria.