## slides for my simulation course

Posted in Books, Kids, R, Statistics, University life with tags , , , , , , , , on October 18, 2012 by xi'an

Similar to last year, I am giving a series of lectures on simulation jointly as a Master course in Paris-Dauphine and as a 3rd year course in ENSAE. The course borrows from both the books Monte Carlo Statistical Methods and from Introduction to Monte Carlo Methods with R, with George Casella. Here are the three series of slides I will use throughout the course this year, mostly for the benefit of the students:

(the last series is much improved when compared with an earlier version, thanks to Olivier Cappé!)

## applied Bayesian statistical modelling (PhD course at CREST)

Posted in Statistics, Travel, University life with tags , , , , , , , , , on April 17, 2012 by xi'an

Next month, Kerrie Mengersen (QUT, Brisbane, Australia, and visiting us at CREST and Paris-Dauphine this coming May) will give a PhD course at CREST on the theme of applied Bayesian statistical modelling.

Here is her abstract:

Bayesian hierarchical models are now widely used in addressing a rich variety of real-world problems. In this course, we will examine some common models and the associated computational methods used to solve these problems, with a focus on environmental and health applications.

Two types of hierarchical models will be considered, namely mixture models and spatial models. Computational methods will cover Markov chain Monte Carlo, Variational Bayes and Approximate Bayesian Computation.

Participants will have the opportunity to implement these approaches using a number of datasets taken from real case studies, including the analysis of digital images from animals and satellites, and disease mapping for medicine and biosecurity.

The classes will take place at ENSAE, Paris, on May 3, 10 (14:00, Amphi 2), 14, and 21 (11:00, Room S8). (The course is open to everyone and free of charge, but registrations are requested, please contact Nadine Guedj.)

## seminar at CREST on predictive estimation

Posted in pictures, Statistics, University life with tags , , , , , , , , on March 6, 2012 by xi'an

On Thursday, March 08, Éric Marchand (from Université de Sherbrooke, Québec, where I first heard of MCMC!, and currently visiting Université de Montpellier 2) will give a seminar at CREST. It is scheduled at 2pm in ENSAE (ask the front desk for the room!) and is related to a recent EJS paper with Dominique Fourdrinier, Ali Righi, and Bill Strawderman: here is the abstract from the paper (sorry, the pictures from Roma are completely unrelated, but I could not resist!):

We consider the problem of predictive density estimation for normal models under Kullback-Leibler loss (KL loss) when the parameter space is constrained to a convex set. More particularly, we assume that

$X \sim \mathcal{N}_p(\mu,v_x\mathbf{I})$

is observed and that we wish to estimate the density of

$Y \sim \mathcal{N}_p(\mu,v_y\mathbf{I})$

under KL loss when μ is restricted to the convex set C⊂ℝp. We show that the best unrestricted invariant predictive density estimator p̂U is dominated by the Bayes estimator p̂πC associated to the uniform prior πC on C. We also study so called plug-in estimators, giving conditions under which domination of one estimator of the mean vector μ over another under the usual quadratic loss, translates into a domination result for certain corresponding plug-in density estimators under KL loss. Risk comparisons and domination results are also made for comparisons of plug-in estimators and Bayes predictive density estimators. Additionally, minimaxity and domination results are given for the cases where: (i) C is a cone, and (ii) C is a ball.

## ABC and Monte Carlo seminar in CREST

Posted in Statistics, University life with tags , , , , , , , on January 13, 2012 by xi'an

On Monday (Jan. 16, 3pm, CREST-ENSAE, Room S08), Nicolas Chopin will present a talk on:

Dealing with intractability: recent advances in Bayesian Monte-Carlo methods for intractable likelihoods
(joint works with P. Jacob, O. Papaspiliopoulos and S. Barthelmé)

This talk will start with a review of recent advancements in Monte Carlo methodology for intractable problems; that is problems involving intractable quantities, typically intractable likelihoods. I will discuss in turn ABC type methods (a.k.a. likelihood-free), auxiliary variable methods for dealing with intractable normalising constants (e.g. the exchange algorithm), and MC² type of algorithms, a recent extension of which being the PMCMC algorithm (Andrieu et al., 2010). Then, I will present two recent pieces of work in these direction. First, and more briefly briefly, I’ll present the ABC-EP algorithm (Chopin and Barthelmé, 2011). I’ll also discuss some possible future research in ABC theory. Second, I’ll discuss the SMC² algorithm (Chopin, Jacob and Papaspiliopoulos, 2011), a new type of MC² algorithm that makes it possible to perform sequential analysis for virtually any state-space models, including models with an intractable Markov transition.

## Jaynes’ back on track!

Posted in Books, Statistics, University life with tags , , on March 30, 2011 by xi'an

Following the cancellation of my reading seminar on Jaynes’ Probability Theory, and requests from several would-be-attendees, I am giving a one-day [crash] course on the book on April 11. It will be at ENSAE, salle 11, from 9:30 till 4:00pm [or earlier if I exhaust the slides, the material or the audience], with a break at noon. Once again, it is open to everyone, but attendants must register with Nadine Guedj [at ensae.fr]. Several copies of Probability Theory are available  in the library. The slides are available as earlier as

Obviously, this is a last call!