The aim of this work is ''building out" the simple Markovian model in a more realistic direction assuming that the time between sequencial purchases is variable. To study the complete relationship between "the marketing input variables" and brand transition, the author proposed to drop completely the analytical solution and instead construct a semi-mathematical model based on the use of an electronical computer. The solution has the following characteristics: 1. Each cell in the transition matrix is a function of series of marketing input variables. The type of function is proposed to be trigonometrical series. As a result of the transition matrix has to be dynamic (varying with time). The author is also discussing the interviewing methods by means of which one can collect the data-material for.