Minimally Conditioned Likelihood for a Nonstationary State Space Model

Computing the gaussian likelihood for a nonstationary state-space model is a difficult problem which has been tackled by the literature using two main strategies: data transformation and diffuse likelihood. The data transformation approach is cumbersome, as it requires nonstandard filtering. On the...

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Bibliographic Details
Authors: Casals Carro, José, Sotoca López, Sonia, Jerez Méndez, Miguel
Format: report
Publication Date:2012
Country:España
Institution:Universidad Complutense de Madrid (UCM)
Repository:Docta Complutense
Language:English
OAI Identifier:oai:docta.ucm.es:20.500.14352/49063
Online Access:https://hdl.handle.net/20.500.14352/49063
Access Level:Open access
Keyword:State-space models
Conditional likelihood
Diffuse likelihood
Diffuse initial conditions
Kalman filter
Nonstationarity.
Econometría (Economía)
5302 Econometría
Description
Summary:Computing the gaussian likelihood for a nonstationary state-space model is a difficult problem which has been tackled by the literature using two main strategies: data transformation and diffuse likelihood. The data transformation approach is cumbersome, as it requires nonstandard filtering. On the other hand, in some nontrivial cases the diffuse likelihood value depends on the scale of the diffuse states, so one can obtain different likelihood values corresponding to different observationally equivalent models. In this paper we discuss the properties of the minimally-conditioned likelihood function, as well as two efficient methods to compute its terms with computational advantages for specific models. Three convenient features of the minimally-conditioned likelihood are: (a) it can be computed with standard Kalman filters, (b) it is scale-free, and (c) its values are coherent with those resulting from differencing, being this the most popular approach to deal with nonstationary data.