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AI-generated Abstract

This paper discusses structural time series models, focusing on their formulation through unobserved components such as trend, seasonal, cycle, and irregular components. It outlines the state space framework that underpins these models, emphasizing the role of filtering in estimating unobserved states and making predictions. The article also highlights recent technical advancements and applications in the field, building upon foundational works by Harvey and Jaeger (1991) and others, while illustrating the estimation procedures and statistical properties of these models.

Key takeaways

  • Stochastic trend components are introduced into dynamic regression models when the underlying level of a nonstationary dependent variable cannot be completely explained by observable explanatory variables.
  • where ILl is a stochastic trend (1.4), Xt is a k x 1 vector of exogenous explanatory variables, [) is a corresponding vector of unknown parameters, 8t is a normally distributed, white noise disturbance term with mean zero and variance a;.
  • This section considers how simultaneous equation models can be estimated when stochastic trend components of the kind described in Section 4 are specified in some or all of the structural equations.
  • , 4Jr are N x N matrices of autoregressive parameters, Bo,..., Bs are N x K matrices of parameters associated with the K x 1 vector of exogenous variables Xt and its lagged values, ILt is an n x 1 vector of stochastic trends, S is an N x n selection matrix of ones and zeros, such that each of the stochastic trends appears in a particular equation, and TIt and Et are mutually independent, normally distributed white noise disturbance vectors with positive definite covariance matrices 1:'1 and 1:.
  • Although stochastic variance models can be made to fit within the linear space framework and so can be handled by using the Kalman filter, this filter does not deliver the optimal (minimum mean square error) estimate.