Such specific properties, as intangibility, namely absence of the material form up to the moment of realization, and impossibility of keeping are typical for the services [1].

The models of process of indirect advertising usually are based on the following basic assumptions [2, 3].

It is considered, that the speed of change in the time of quantity of the clients knowing about the object of advertising and ready to its purchase, is proportional to both quantity of buyers knowing about it, and quantity of buyers, not knowing about it. Also it is supposed, that to the moment of the beginning of process the some part from the total of the potential buyers already knows about object of the advertising.

Also a degree of dialogue of the buyers among themselves plays important role, influencing on the time and the speed of distribution of indirect advertising in the mentioned models.

According to existing representations [2, 3], analysis of speed of distribution of indirect advertising is based on the differential equation of the first order:

, (1)

where is the distribution speed of indirect advertising,

is the degree of dialogue of the buyers among themselves, ,

is the quantity of the clients knowing about the object of advertising to the moment ,

is the total quantity of the potential buyers,

is the quantity of the clients, not knowing about the object of advertising to the moment ; at the initial conditions , where .

It was suggested in [2] to determine the value by means of the interrogations.

However, the other possible approach is based on the existing formula of change values of any information in the time, including information received by indirect advertising.

Value of the information in the time tends to decrease, according to the dependence [4]:

, (2)

where - value of the information in the moment of occurrence or reception ( );

*t* - time from the moment of occurrence of the information up to the moment of definition of value;

- time from the moment of occurrence of the information up to the moment of the aging ( ).

As it is visible from the earlier considered equation (1), the speed of distribution of indirect advertising is directly proportional to a degree of dialogue of the buyers among themselves. The mentioned degree is the some coefficient of the proportionality. Considering, that on the average degree of dialogue of the buyers with each other about the goods or service is completely defined by value of the advertising information about object of advertising, we shall come to the following modified model of speed of distribution of indirect advertising:

, (3)

where the designations are coincide with specified in explanations of the formulas (1) and (2).

Within positions of sociology and marketing the research of time and speed of distribution of indirect advertising is of interest at various initial value of advertising information and at various periods of time, during which the advertising information has a value.

The considered equation (3) is the differential equation with dividing variables, with the non-zero initial condition. The analytical solution of the specified equation gives in result the particular solution, which is suitable for the analysis:

.

The work was submitted to the International Scientific Conference « Economics and Management», Thailand, December 20-30, 2009. Came to the editorial office on 15.11.2009.