Abstract. In this article the authors present the main aspects of a country's macroeconomic system. It shows that it is a complex structured economic sectors (pure sectors). Also it makes reference to the free market, placing the problem of identifying the interaction of market forces. Inside the national economy there is an intermediate consumption that is showing the amount consumed by branch "c" from all other branches. Input fields are used in this respect in order to show that at a macroeconomic level the model is complex, on the basis of the model calculation and analysis of economic is performed. On the basis of coefficients the existence and intensity of links between branches of national economy is determined. It is important to establish the how aggregation of branches is taking place. The number of branches and the concentration degree are subordinate requirements of study links and proportions that are performed in an economic activity. Aggregation of activities in order to establish the branches used for creating input-output tables is made according to several criteria such as: product identification, common destination of the finished product, similarity raw materials consumed or technological processes and likeness of quantitative structure cost price of production.

The branches for the balance should be homogeneous and represent a grouping of homogeneous production units.

Keywords: forecasting, production, intermediary consumption, technology, coefficient, matrix.