This paper reports the analysis of a forecasting prob­lem based on time series. It is noted that the forecasting stage itself is preceded by the stages of selection of fore­casting methods, determining the criterion for the fore­cast quality, and setting the optimal prehistory step. As one of the criteria for a forecast quality, its volatility has been considered. Improving the volatility of the forecast could ensure a decrease in the absolute value of the devi­ation of forecast values from actual data. Such a crite­rion should be used in forecasting in medicine and other socially important sectors.To implement the principle of competition between forecasting methods, it is proposed to categorize them based on the values of deviations in the forecast results from the exact values of the elements of the time series. The concept of dominance among forecasting methods has been introduced; rules for the selection of domi­nant and accurate enough predictive models have been defined. Applying the devised rules could make it pos­sible, at the preceding stages of the analysis of the time series, to reject in advance the models that would sure­ly fail from the list of predictive models available to use.In accordance with the devised method, after apply­ing those rules, a system of functions is built. The func­tions differ in the sets of predictive models whose fore­casting results are taken into consideration. Variables in the functions are the weight coefficients with which predictive models are included. Optimal values for the variables, as well as the optimal model, are selected as a result of minimizing the functions built.The devised method was experimentally verified. It has been shown that the constructed method made it possible to reduce the forecast error from 0.477 and 0.427 for basic models to 0.395 and to improve the volatili­ty of the forecast from 1969.489 and 1974.002 to 1607.065 © 2021, Authors. This is an open access article under the Creative Commons CC BY license