Macroeconomic models with non-zero dispersion

摘要

Using two simple stochastic dynamic models, this paper demonstrates that the coefficient of variation of aggregate output, GDP, does not necessarily go to zero when the number of sectors or economic agents goes to infinity. This paper shows that this phenomenon, known as non-self averaging in physics, occurs in the two-parameter Poisson-Dirichlet models, and in certain balanced triangular urn models of growth. This implies that the standard microeconomic functions for aggregate outpu based on the representative agent models have little value, since these models do not provide us with better picture of the long-run behavior of the model. The paper also shows both models have a generalized Mittag-Leffler density function, which has power-law tail.