Une représentation de l'économie française : le modèle DMS

Abstract

[fre] Modelling French economy : DMS . INSEE. Service des Programmes. Macro-economic forecasts used during the preparation of the VIIIth (1981-1985) french Plan were built with the help of a dynamic macro-econometric model. This model, called DMS (Dynamique Multi Sectoriel), has been developed from 1974 to 1976 at thé INSEE (Service des Programmes).. The most direct approach to DMS consists in a survey of its main equations. Three important features appears then : the role of time-lags for dynamic properties of the projections ; a complete description for eleven sectors, including price determination ; in each of the three manufacturing industries a clay-clay vintage model implies a sort of memory for thé economy on médium term outlook. . However a model cannot be summarized by the list of its equations. It involves many kinds of relationships between institutional sectors and simulates regulation procedures like in the real economy. According to DMS, most of these relationships relies on the twin-aspects of capital, both physical and financial matter of économie behaviour. Key desequilibrium-indicators are bound to these aspects : the degree of utilization of capacity and the profit rate; they order regulation processes, especially the moves of prices and investment from year to year. . How sophisticated the model maybe, it remains a very rough figure compared with economic reality. Econometric methods are based on statistical data analyses, refering to years ago ; are they really able to underly projections in the future ? . Business fixed investment funitions of DMS model depends on profit rates, especially in the non-industrial sectors, how far can it be expected that accelarator effects have nowadays a greater influence ? DMS includes no monetary and financial sector ; what sort of discrepanciesmay result from external hypothesis on irïterest rates and external exchange rates ? The DMS-team of economist had to answer those basic questions1 in each working parties designed to prépare the VIIIth Plan. Part of the answer s are given in the paper, waiting for new improvement in statistical and economic research or analysis.