ARMA models provide a parsimonious and flexible mechanism for modeling the evolution of a time series. Some useful measures of these models (e.g., the autocorrelation function or the spectral density function) are tedious to compute by hand. This paper uses a computer algebra system, not...

We prove a representation of the partial autocorrelation function (PACF) of a stationary process, or of the Verblunsky coefficients of its normalized spectral measure, in terms of the Fourier coefficients of the phase function. It is not of fractional form, whence simpler than the existing one...

This paper shows that aggregation over heterogeneous firms, which are subject to temporary technology shocks, will lead to long memory and nonlinearities. We start from microfoundations, using standard RBC model of monopolistic competition. We then derive the fundamental intertemporal...

This paper shows that the behaviour of an otherwise conventional model of real business cycles (RBCs) in which heterogeneous individual firms are subject to temporary technology shocks will be characterised by long memory and nonlinearity. We start from microfoundations, using a standard RBC...