In this paper we build on previous work which uses inferences techniques, in
particular Markov Chain Monte Carlo (MCMC) methods, to solve parameterized
control problems. We propose a number of modifications in order to make this
approach more practical in general, higher-dimensional spaces. We first
introduce a new target distribution which is able to incorporate more reward
information from sampled trajectories. We also show how to break strong
correlations between the policy parameters and sampled trajectories in order to
sample more freely.
Sequential Monte Carlo (SMC) methods are a class of techniques to sample
approximately from any sequence of probability distributions using a
combination of importance sampling and resampling steps. This paper is
concerned with the convergence analysis of a class of SMC methods where the
times at which resampling occurs are computed online using criteria such as the
effective sample size. This is a popular approach amongst practitioners but
there are very few convergence results available for these methods.
Sparsity-promoting priors have become increasingly popular over recent years
due to an increased number of regression and classification applications
involving a large number of predictors. In time series applications where
observations are collected over time, it is often unrealistic to assume that
the underlying sparsity pattern is fixed. We propose here an original class of
flexible Bayesian linear models for dynamic sparsity modelling. The proposed
class of models expands upon the existing Bayesian literature on sparse
regression using generalized multivariate hyperbolic distributions.
This report is a collection of comments on the Read Paper of Fearnhead and
Prangle (2011), to appear in the Journal of the Royal Statistical Society
Series B, along with a reply from the authors.
While statisticians are well-accustomed to performing exploratory analysis in
the modeling stage of an analysis, the notion of conducting preliminary
general-purpose exploratory analysis in the Monte Carlo stage (or more
generally, the model-fitting stage) of an analysis is an area which we feel
deserves much further attention. Towards this aim, this paper proposes a
general-purpose algorithm for automatic density exploration.
Let $\mathscr{P}(E)$ be the space of probability measures on a measurable
space $(E,\mathcal{E})$. In this paper we introduce a class of nonlinear Markov
chain Monte Carlo (MCMC) methods for simulating from a probability measure
$\pi\in\mathscr{P}(E)$. Nonlinear Markov kernels (see [Feynman--Kac Formulae:
Genealogical and Interacting Particle Systems with Applications (2004)
Springer]) $K:\mathscr{P}(E)\times E\rightarrow\mathscr{P}(E)$ can be
constructed to, in some sense, improve over MCMC methods.
Sequential Monte Carlo methods, also known as particle methods, are a widely
used set of computational tools for inference in non-linear non-Gaussian
state-space models. In many applications it may be necessary to compute the
sensitivity, or derivative, of the optimal filter with respect to the static
parameters of the state-space model; for instance, in order to obtain maximum
likelihood model parameters of interest, or to compute the optimal controller
in an optimal control problem. In Poyiadjis et al.
We explore the use of generalized t priors on regression coefficients to help
understand the nature of association signal within "hit regions" of genome-wide
association studies. The particular generalized t distribution we adopt is a
Student distribution on the absolute value of its argument. For low degrees of
freedom we show that the generalized t exhibits 'sparsity-prior' properties
with some attractive features over other common forms of sparse priors and
includes the well known double-exponential distribution as the degrees of
freedom tends to infinity.
Sequential Monte Carlo (SMC) methods are a widely used set of computational
tools for inference in non-linear non-Gaussian state-space models. We propose a
new SMC algorithm to compute the expectation of additive functionals
recursively. Essentially, it is an online or forward-only implementation of a
forward filtering backward smoothing SMC algorithm proposed in Doucet .et .al
(2000).
Switching state-space models (SSSM) are a very popular class of time series
models that have found many applications in statistics, econometrics and
advanced signal processing. Bayesian inference for these models typically
relies on Markov chain Monte Carlo (MCMC) techniques. However, even
sophisticated MCMC methods dedicated to SSSM can prove quite inefficient as
they update potentially strongly correlated discrete-valued latent variables
one-at-a-time (Carter and Kohn, 1996; Gerlach et al., 2000; Giordani and Kohn,
2008).
This is a collection of discussions of `Riemann manifold Langevin and
Hamiltonian Monte Carlo methods" by Girolami and Calderhead, to appear in the
Journal of the Royal Statistical Society, Series B.
We present a new class of interacting Markov chain Monte Carlo algorithms for
solving numerically discrete-time measure-valued equations. The associated
stochastic processes belong to the class of self-interacting Markov chains. In
contrast to traditional Markov chains, their time evolutions depend on the
occupation measure of their past values. This general methodology allows us to
provide a natural way to sample from a sequence of target probability measures
of increasing complexity.
Variable selection techniques have become increasingly popular amongst
statisticians due to an increased number of regression and classification
applications involving high-dimensional data where we expect some predictors to
be unimportant.
This paper presents a new approach for channel tracking and parameter
estimation in cooperative wireless relay networks. We consider a system with
multiple relay nodes operating under an amplify and forward relay function. We
develop a novel algorithm to efficiently solve the challenging problem of joint
channel tracking and parameters estimation of the Jakes' system model within a
mobile wireless relay network. This is based on a novel particle Markov chain
Monte Carlo (PMCMC) method.
We design a particle interpretation of Feynman-Kac measures on path spaces
based on a backward Markovian representation combined with a traditional mean
field particle interpretation of the flow of their final time marginals. In
contrast to traditional genealogical tree based models, these new particle
algorithms can be used to compute normalized additive functionals "on-the-fly"
as well as their limiting occupation measures with a given precision degree
that does not depend on the final time horizon.