Archive for Tyne

optimal importance sampling

Posted in Books, pictures, Statistics, University life with tags , , , , , , , , on May 31, 2023 by xi'an

In Stein Π-Importance Sampling, Congye Wang et al. (mostly from Newcastle, UK) build an MCMC scheme with invariant distribution Π targeting a distribution P, showing that the optimal solution (in terms of a discrepancy) differs from P when the chain is Stein-sampled, e..g. via kernel discrepancies. In terms of densities, the solution is

\pi^\star(x)\propto p(x)k_P(x)^{1/2}

the correction involving the root of a Stein kernel, introduced by Oates, Girolami, and Chopin in their 2017 Series B Read Paper. This is rather paradoxical, even though the outcome does depend on the divergence criterion. Most intriguing!!!

guess what..?! Yet another worskhop in the endless summer Bayesian series!

Posted in Mountains, pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , on April 18, 2018 by xi'an

Dennis Prangle pointed to me the perfectly timed i-like workshop taking place in Newcastle, on the days priors to ABC in Edinburgh and ISBA (similarly in Edinburgh!). (Note that Warwick is also part of the i-like network. Actually, the first i-like workshop was my first trip abroad after the Accident!) I may sound negative about these workshops, but on the opposite am quite a fan of them, just regretting that the main event did not take advantage of them all to reduce the volume of talks there. As I suggested, it could have been feasible to label these satellites as part of the main conference towards making speakers at these officially speakers at ISBA 2018 in case talks were required for support…

The i-like workshop 2018 is the sixth edition of a yearly series of workshops dedicated to the topic of intractable likelihoods, hosted by Newcastle University. The workshop will take place from Wednesday 20 June 2018 – Friday 22 June 2018 in Room 2.98, Armstrong Building, Newcastle upon Tyne. Registration is free and mandatory!

I spent a few days in Newcastle at the RSS meeting of 2013, with my friends Jim Hobert and Elias Moreno. Enjoying very much the city, its surroundings, the great meadow north of the city in a glorious sunset (I still bemoan not catching on camera!). And it is just in the vicinity of Hadrian’s Wall, just on the other side of the Borders, very close to Edinburgh in fact.