In appraisal of the market value of a real property the main focus is done on studies of the real properties market and selection of adequate data - the features characterizing the real properties which are being appraised. The selection of features is done individually by the appraiser on the bases of his knowledge and experience. As consequence of the above the following questions were risen: 1. Which features of real properties used for appraisal have the major influence on the behavior of clients in the market and their readiness to pay the transaction price?. 2. What level of quality and precision of data collection and processing should be maintained to satisfy the needs of appraisal, i.e. that the appraised value is closest to the sales price? The authors of this paper have tested the local real properties market to answer the above questions. Also, the sensitivity analysis of real property value to changes in accuracy and precision of input data for appraisal of that value performed. In the following paper the authors present the results of their studies as well as the conclusions and observations generated during the researching work.