On line and on site real estate appraisals in Italy

In Italy, on the web sites spread on line appraisals of the real estate founded on the list of value range, on the list of market price and on other generic sources. Every web site offers more than an appraisal for the same basis of valuation: the same property can present different values simultaneously. The on line valuation apply the expertise on mass appraisal without the collection of the single data. The potential number of the errors, related to the difference among appraisals and market prices, and the number of the divergences among the appraisal of the different operators can be quantified. Despite the absence of statistic data can be prefigured a loss function, based on the error and divergences, assigning probability and penalty. In the international sites, the on line appraisals are founded on the market prices of comparable properties with the property estimated. The value is a computer-generated appraisal using a proprietary formula. The principal differences among the two realities concern the definition of the esteemed value, the source of the input data and the procedures of valuation.