The appraisal smooting in the real estate indices

The appraisal smoothing is the phenomenon in which the valuation of a property, based on the judgments of appraisers (expertise) rather than on the collection of market data, is influenced by previous valuations performed by the same expert. The most obvious consequence of the exercise of expertise is the tendency to generate in the time a smoothing in the estimated value. This is the first experimental application of the appraisal smoothing theory in Italy. The general spread of real estate valuations, based on prices and average prices refer to a single commercial parameter (usually the surface), generates the natural suspicion that the smoothing effect could be widely disseminated and the practical certainty of his presence. The study aims to measure this effect through an experimental case using a sample of urban real estate sales for the period of five years. The research applies deterministic and econometric models to counteract the appraisal smoothing based on the results of the statistical analysis of the data, on the basis of literature and direct observation of the phenomenon.