Dynamic sparsity on dynamic regression models
- URL: http://arxiv.org/abs/2009.14131v1
- Date: Tue, 29 Sep 2020 16:26:08 GMT
- Title: Dynamic sparsity on dynamic regression models
- Authors: Paloma W. Uribe and Hedibert F. Lopes
- Abstract summary: We consider variable selection and shrinkage for the Gaussian dynamic linear regression within a Bayesian framework.
We propose a novel method that allows for time-varying sparsity, based on an extension of spike-and-slab priors for dynamic models.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: In the present work, we consider variable selection and shrinkage for the
Gaussian dynamic linear regression within a Bayesian framework. In particular,
we propose a novel method that allows for time-varying sparsity, based on an
extension of spike-and-slab priors for dynamic models. This is done by
assigning appropriate Markov switching priors for the time-varying
coefficients' variances, extending the previous work of Ishwaran and Rao
(2005). Furthermore, we investigate different priors, including the common
Inverted gamma prior for the process variances, and other mixture prior
distributions such as Gamma priors for both the spike and the slab, which leads
to a mixture of Normal-Gammas priors (Griffin ad Brown, 2010) for the
coefficients. In this sense, our prior can be view as a dynamic variable
selection prior which induces either smoothness (through the slab) or shrinkage
towards zero (through the spike) at each time point. The MCMC method used for
posterior computation uses Markov latent variables that can assume binary
regimes at each time point to generate the coefficients' variances. In that
way, our model is a dynamic mixture model, thus, we could use the algorithm of
Gerlach et al (2000) to generate the latent processes without conditioning on
the states. Finally, our approach is exemplified through simulated examples and
a real data application.
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