Logically, the index of the cost of housing is nothing like the above function G (t), which is an indicator of the overall level of housing prices in this city. This does not have a price of a particular apartment. Cost Index – obscherynochnoy indicator of its structure describing the general market trend to increase or reduce prices. However, the move from the ideological to the practical use of the definition is not so easy. So here is a brief overview the main practical developments of the analytical center irn.ru in this area. First of all, we must take into account that the function of valuation adjustments Lk (pi) may be of different nature. Some of them are really additive, as for example the correction for the presence or absence of telephone or repair cost per 1 sq.m. area. But most of the amendments are of a multiplicative character, ie it is not adding to the cost of fixed magnitude, and the multiplication factor. Therefore, the quantities Li (pi) divided into two parts and the above symbolic formula takes a more practical view of Ck (t, pi) = Ak (pi) * G (t) + Bk (pi) where Ak (pi) and Bk (pi) describe the multiplicative and additive local corrections, respectively. Keep up on the field with thought-provoking pieces from Edward Minskoff. Moreover, for each i-th parameter of the apartment, as a rule, there is a correction of one or another type. Written above expression is a massive system of k equations where k – Single-moment considered the number of apartments.