Archive for Russian doll
нет войнe
Posted in Kids, pictures with tags нет войне, figurines, Instagram, Mir, New York T, Russian doll, Russian invasion, Solidarity with Ukraine, Stop the War on July 2, 2023 by xi'an
a day for comments
Posted in Mountains, Statistics, Travel, University life with tags AISTATS 2014, Bayesian variable selection, Brad Carlin, Cuillin ridge, Gaussian mixture, Gibbs sampler, hierarchical models, Iceland, ICML, Langevin MCMC algorithm, MCMC, Metropolis-Hastings algorithms, mixtures, model complexity, penalisation, reference priors, Reykjavik, RJMCMC, Russian doll, Scotland, sequential Monte Carlo, Sid Chib, Skye, speedup, spike-and-slab prior, variable dimension models on April 21, 2014 by xi'an
As I was flying over Skye (with [maybe] a first if hazy perspective on the Cuillin ridge!) to Iceland, three long sets of replies to some of my posts appeared on the ‘Og:
- Dan Simpson replied to my comments of last Tuesday about his PC construction;
- Arnaud Doucet precised some issues about his adaptive subsampling paper;
- Amandine Schreck clarified why I had missed some points in her Bayesian variable selection paper;
- Randal Douc defended the efficiency of using Carlin and Chib (1995) method for mixture simulation.
Thanks to them for taking the time to answer my musings…
Dan Simpson’s seminar at CREST
Posted in Kids, Mountains, Statistics, Travel, University life with tags Banff, BiPS, CREST, hierarchical models, model complexity, Paris, penalisation, reference priors, Russian doll, Russian roulette on April 18, 2014 by xi'an
Daniel Simpson gave a seminar at CREST yesterday on his recently arXived paper, “Penalising model component complexity: A principled, practical approach to constructing priors” written with Thiago Martins, Andrea Riebler, Håvard Rue, and Sigrunn Sørbye. Paper that he should also have given in Banff last month had he not lost his passport in København airport… I have already commented at length on this exciting paper, hopefully to become a discussion paper in a top journal!, so I am just pointing out two things that came to my mind during the energetic talk delivered by Dan to our group. The first thing is that those penalised complexity (PC) priors of theirs rely on some choices in the ordering of the relevance, complexity, nuisance level, &tc. of the parameters, just like reference priors. While Dan already wrote a paper on Russian roulette, there is also a Russian doll principle at work behind (or within) PC priors. Each shell of the Russian doll corresponds to a further level of complexity whose order need be decided by the modeller… Not very realistic in a hierarchical model with several types of parameters having only local meaning.
My second point is that the construction of those “politically correct” (PC) priors reflects another Russian doll structure, namely one of embedded models, hence would and should lead to a natural multiple testing methodology. Except that Dan rejected this notion during his talk, by being opposed to testing per se. (A good topic for one of my summer projects, if nothing more, then!)
