Statistical Features of Complex Systems –Toward Establishing Sociological Physics–

Abstract

Complex systems have recently attracted much attention, both in natural sciences and in sociological sciences.Members constituting a complex system evolve through nonlinear interactions among each other.This means that in a complex system the multiplicative experience or, so to speak, the history of each member produces its present characteristics.If attention is paid to any statistical property in any complex system, the lognormal distribution is the most natural and appropriate among the standard or ''normal'' statistics to overview the whole system.In fact, the lognormality emerges rather conspicuously when we examine, as familiar and typical examples of statistical aspects in complex systems, the nursing-care period for the aged, populations of prefectures and municipalities, and our body height and weight.Many other examples are found in nature and society.On the basis of these observations, we discuss the possibility of sociological physics.