The sales comparison approach (SCA) is a real estate appraisal valuation method that relies on the assumption that a matrix of attributes or significant features of a property drive its value.
Research has shown that the sales adjustment grid and the multiple regression model are theoretically the same, with the former applying more heuristic methods and the latter using statistical techniques.
Given property inflation and price cycles, both comparison techniques can become unreliable if the time interval between transactions sampled is excessive.
The other factor undermining a simplistic use of the SCA is the evolving nature of city neighborhoods, though in reality urban evolution occurs gradually enough to minimize its impact on this approach to value.
In more complex situations, such as litigation or contaminated property appraisal, appraisers develop SCA adjustments using widely accepted advanced techniques, such as repeat sales models (to measure house price appreciation over time), survey research (e.g. -- contingent valuation), case studies (to develop adjustments in complex situations) or other statistically based techniques.