Appraisals are based on regression models. Its major application limits are all in situations in which the real estate market doesn't offer a sufficient number of comparables to implement statistical tools. In low-transaction real estate markets, the most effective appraisal method is the market comparison approach (MCA). The application limits of MCA depend on the degree of similarity between the properties' characteristics and the reliability of the prices of comparables. In this paper, we introduce some rational measurements in order to guarantee a scientific approach to MCA is associated with the correct prices. Our method is able to restore appraisals of the market value of any type of property, even in situations in which the comparables are limited or when the reliability of the buying and selling prices could be better.The International Valuation Standards (IVS) are internationally recognized appraisal methods used in the market-oriented approach, the income approach, and the cost approach. When a real estate market is active and all necessary market data are available, the market comparison approach (MCA) is the most direct, probative, and documented method used to appraise real estate market values (Simonotti, 2006); in particular, the MCA is the most important method and is comparable to the marketoriented approach. The MCA is known by several different names in the appraisal literature. In some of the older literature it is called the market data approach, while elsewhere it is referred to as the grid adjustment technique.There are many appraisal procedures that can be used in the logic application of the MCA. These procedures are grouped into two categories: (1) quantitative techniques based on detection of objective markets data (paired data analysis, graphic analysis, trend analysis, secondary data analysis, adjustment grid method, etc.); and (2) qualitative techniques based on the analyst's subjective judgment (relative comparison analysis, personal interviews, etc.).