Unlike linear ones, nonlinear business cycle models can generate sustained fluctuations even in the absence of shocks (e.g., via limit cycles/chaos). A popular approach to solving nonlinear models is perturbation methods. I show that, as typically implemented, these methods are incapable of...

A number of studies have found that news shocks account for a large part of the aggregate fl uctuations of the main macroeconomic variables.We show that when taking rational expectations into consideration there is a limit on the size of the variance of the news shocks,which has not been...