Archive for Bayesian inference

permutations accelerate ABC!

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , , , , , , , , , , , , , , , on July 9, 2025 by xi'an

Yesterday a arXival by Antoine Luciano, Charly Andral (both PhD students, now or then, at Paris Dauphine), Robin Ryder (formerly at Paris Dauphine, now at Imperial College London) and myself got posted. It proposes to improve the scalability of ABC methods by exploiting the (full or partial) exchangeability in the data by implementing permutation-based matching between observed and simulated samples. This significantly improves computational efficiency, which is further enhanced by sequential strategies such as over-sampling, which facilitates early-stage acceptance by temporarily increasing the number of simulated compartments, and under-matching, which relaxes the acceptance condition by matching only subsets of the data. The map of France appears in connection with an application of the method to estimating SIR parameters, department by department. (It is also reminding me of the cover of Markov Chain Monte Carlo methods in practice, the 1996 contributed book edited by Wally Gilks, Sylvia Richardson and David Spiegelhalter.)

exceptional OWABI web/sem’inar [19 June, BayesComp²⁵]

Posted in pictures, Statistics, Travel, Uncategorized, University life with tags , , , , , , , , , , , , , , on June 10, 2025 by xi'an


Exceptionally, the next One World Approximate Bayesian Inference (OWABI) Seminar will be hybrid as it is scheduled to take place during BayesComp 2025 in Singapore, on Thursday 19 June at 8pm Singapore time (1pm in Tórshavn) and two talks, one by Filippo Pagani on

Approximate Bayesian Fusion
Bayesian Fusion is a powerful approach that enables distributed inference while maintaining exactness. However, the approach is computationally expensive. In this work, we propose a novel method that incorporates numerical approximations to alleviate the most computationally expensive steps, thereby achieving substantial reductions in runtime. Our approach retains the flexibility to approximate the target posterior distribution to an arbitrary degree of accuracy, and is scalable with respect to both the size of the dataset and the number of computational cores. Our method offers a practical and efficient alternative for large-scale Bayesian inference in distributed environments.
and one by Maurizio Filippone on
GANs Secretly Perform Approximate Bayesian Model Selection
Generative Adversarial Networks (GANs) are popular models achieving impressive performance in various generative modeling tasks. In this work, we aim at explaining the undeniable success of GANs by interpreting them as probabilistic generative models. In this view, GANs transform a distribution over latent variables Z into a distribution over inputs X through a function parameterized by a neural network, which is usually referred to as the generator. This probabilistic interpretation enables us to cast the GAN adversarial-style optimization as a proxy for marginal likelihood optimization. More specifically, it is possible to show that marginal likelihood maximization with respect to model parameters is equivalent to the minimization of the Kullback-Leibler (KL) divergence between the true data generating distribution and the one modeled by the GAN. By replacing the KL divergence with other divergences and integral probability metrics we obtain popular variants of GANs such as f-GANs, Wasserstein-GANs, and Maximum Mean Discrepancy (MMD)-GANs. This connection has profound implications because of the desirable properties associated with marginal likelihood optimization, such as (i) lack of overfitting, which explains the success of GANs, and (ii) allowing for model selection, which opens to the possibility of obtaining parsimonious generators through architecture search.

These talks will be delivered on-site and on-line, as a Zoom visio-conference.

tenets of quantile-based inference in Bayesian models

Posted in Books, Statistics with tags , , , , , , , , , , , , , , on June 8, 2025 by xi'an

This 2023 paper of Perepolkin, Goodrich, and Sahlin vaguely relates to our insufficient Gibbs work in that a Bayesian analysis is conducted based solely on quantile summaries. Except that here the input is the entire cdf, or the—inverse cdf—quantile function, or—its derivative—the quantile density function, instead of the probability density function—used as the likelihood in the posterior. Which is a non-problem from a mathematical perspective since all these functions describe the same probability distribution. Which makes the following quote rather puzzling (in its obviousness).

“We aim to show that the quantile-based Bayesian inference using the intermediate depths leads to the same posterior beliefs as the conventional density-based inference.”

The authors still make a big case of the difference, obviously, to the point of proposing a different notation for Y~F. But using the same symbol f for different densities. The formal expression of the posterior based on the quantile function actually requires the cdf function and the density or the quantile density to be available (at least in a numerical sense), witness eqn (11).

The paper still could hold some interest in its computational component. Relating to ABC, obviously, since distributions defined by quantiles and cdfs often come as benchmarks for ABC, when the associated pdf/likelihood is unavailable. Witness g-and-k distributions (with the caveat MCMC can be implemented in this case). Unfortunately, the paper entirely relies on numerical inversion (with a puzzling comment that MCMC rejection gets higher with numerical inversion, p6). And only mentions ABC in the conclusion, possibly to pacify a referee’s comment. And actually consider that “quantile parameterized quantile distributions don’t lend themselves easily as sampling distributions due to the special nature of their parameterization” (p4). Hence making me wonder at the overall relevance of the entire endeavour….

integral priors for model comparison [2.0]

Posted in Books, Statistics, University life with tags , , , , , , , , , , , , , , , on May 2, 2025 by xi'an

next OWABI webinar [24 April]

Posted in pictures, Statistics, Uncategorized, University life with tags , , , , , , , , , , , , on April 16, 2025 by xi'an


The next One World Approximate Bayesian Inference (OWABI) Seminar is scheduled on Thursday the 24th of April at 11am UK time (12am CET) with the speaker being Ayush Bharti (Aalto University), who will talk about

“Cost-aware simulation-based inference “

Abstract: Simulation-based inference (SBI) is the preferred framework for estimating parameters of intractable models in science and engineering. A significant challenge in this context is the large computational cost of simulating data from complex models, and the fact that this cost often depends on parameter values. We therefore propose cost-aware SBI methods which can significantly reduce the cost of existing sampling-based SBI methods, such as neural SBI and approximate Bayesian computation. This is achieved through a combination of rejection and self-normalised importance sampling, which significantly reduces the number of expensive simulations needed. Our approach is studied extensively on models from epidemiology to telecommunications engineering, where we obtain significant reductions in the overall cost of inference. .