Abstract

In the present study are presented some investigations published on world periodic, which concern to whether the inherent non-stationaryity of macroeconomic time series is entirely due to a random walk or also to non-linear components. Applying the numerical tools of the analysis of dynamical systems to long-run time series for the US, we reject the hypothesis that solely a linear stochastic process generates these series. Contrary to the real business cycle theory that attributes the irregular behaviour of the system to exogenous random factors, we maintain that the fluctuations in the time series we examined cannot lie explained only by means of external shocks plugged into linear autoregressive models.