ABSTRACT
Every social production varies in a particular way0 The number of such variations in economic activity is steadily increasing, and they appear simultaneously, overlapping one another. They differ in many of their characteristics. In the firs t place, the causal factors underlying the variations differ, depending on whether such factors are permanent or tran s i tory, endogenous or exogenous, constant or variable0 They also differ in their varying impact on economic growth, in their duration, relative regularity of occurrence, and in whether they affect the entire economy or only some branches. Although economic dynamics must be viewed as a unique and a complex phe nomenon, numerous differences and specificities, and notably differences in basic underlying fac tors, give these movements a certain degree of relative independence. This simultaneously facili tates and justifies a separate investigation aimed at a deeper comprehension and understanding of different types of variation in economic activity,
as well as of their aggregate impacto Starting from the usual systematization, which
is based on the duration of various forms of economic dynamics, we may identify the parallel existence of short-run, medium-run, and longrun variations of economic activity. Short-run variations include seasonal variations, temporary fluctuations due to the variable effect of natural factors, cyclical oscillations caused by the influ ence of the foreign market, and the like. Longrun variations consist for the most part of great structural changes in the economy, occurring, as a rule, in longer intervals as a phenomenon inherent in the economic development itself. These long-run movements are usually due to great technical upheavals and often extend over a period of several decades. Unlike the duration of short-run variations, the identification of which is relatively easy because of their fre quency, the duration of long-run trends, rep re senting deeper qualitative changes in the economy, cannot be identified easily; the la tte r depend on the degree of economic development and on the scope of the change itself. Long-run variations,
which are the expression of different stages in economic development, cannot repeat themselves in the context of the national economy several tim es in the same way.
