The Stochastic Stationary Root Model

Abstract

We propose and study the stochastic stationary root model. The model resembles the cointegrated VAR model but is novel in that: (i) the stationary relations follow a random coefficient autoregressive process, i.e., exhibhits heavy-tailed dynamics, and (ii) the system is observed with measurement error. Unlike the cointegrated VAR model, estimation and inference for the SSR model is complicated by a lack of closed-form expressions for the likelihood function and its derivatives. To overcome this, we introduce particle filter-based approximations of the log-likelihood function, sample score, and observed Information matrix. These enable us to approximate the ML estimator via stochastic approximation and to conduct inference via the approximated observed Information matrix. We conjecture the asymptotic properties of the ML estimator and conduct a simulation study to investigate the validity of the conjecture. Model diagnostics to assess model fit are considered. Finally, we present an empirical application to the 10-year government bond rates in Germany and Greece during the period from January 1999 to February 2018.

Celebrated Econometricians: Katarina Juselius and Søren Johansen

“…A fourth set of four papers is concerned with modeling and forecasting (Castle et al 2017;Haldrup and Rosenskjold 2019;Hetland 2018;Hoover 2020). Hetland (2018) proposes and discusses an extension of the CVAR model called the Stochastic Stationary Root Model. Properties of the process are discussed.…”