Archive for Scottish independence referendum

better together?

Posted in Books, Mountains, pictures, Statistics, University life with tags , , , , , , , , on August 31, 2017 by xi'an

Yesterday came out on arXiv a joint paper by Pierre Jacob, Lawrence Murray, Chris Holmes and myself, Better together? Statistical learning in models made of modules, paper that was conceived during the MCMski meeting in Chamonix, 2014! Indeed it is mostly due to Martyn Plummer‘s talk at this meeting about the cut issue that we started to work on this topic at the fringes of the [standard] Bayesian world. Fringes because a standard Bayesian approach to the problem would always lead to use the entire dataset and the entire model to infer about a parameter of interest. [Disclaimer: the use of the very slogan of the anti-secessionists during the Scottish Independence Referendum of 2014 in our title is by no means a measure of support of their position!] Comments and suggested applications most welcomed!

The setting of the paper is inspired by realistic situations where a model is made of several modules, connected within a graphical model that represents the statistical dependencies, each relating to a specific data modality. In a standard Bayesian analysis, given data, a conventional statistical update then allows for coherent uncertainty quantification and information propagation through and across the modules. However, misspecification of or even massive uncertainty about any module in the graph can contaminate the estimate and update of parameters of other modules, often in unpredictable ways. Particularly so when certain modules are trusted more than others. Hence the appearance of cut models, where practitioners  prefer skipping the full model and limit the information propagation between these modules, for example by restricting propagation to only one direction along the edges of the graph. (Which is sometimes represented as a diode on the edge.) The paper investigates in which situations and under which formalism such modular approaches can outperform the full model approach in misspecified settings. By developing the appropriate decision-theoretic framework. Meaning we can choose between [several] modular and full-model approaches.

Scottish polls…

Posted in pictures, Statistics, Travel with tags , , , , , , , , on September 11, 2014 by xi'an

Hillhead Street from the Great Western Road, Glasgow westside, Apr. 20, 2012As much as I love Scotland, or because of it, I would not dream of suggesting to Scots that one side of the referendum sounds better than the other. However, I am rather annoyed at the yoyo-like reactions to the successive polls about the result, because, just like during the US elections, each poll is analysed separately rather than being pooled with the earlier ones in a reasonable meta-analysis… Where is Nate Silver when we need him?!

Saints of the Shadow Bible [book review]

Posted in Books, Travel with tags , , , , , on June 14, 2014 by xi'an

The saints of the shadow Bible following me
From bar to bar to eternity’
Jackie Leven

For once, I read my Rankin in Edinburgh, the very place where it takes place! (Somewhere in the book, Rebus acknowledge he never left Scotland. Which does not sound coherent with trips to London in earlier books… Like Tooth and Nails.) It makes the lecture much more complete, as I could picture some of the places and partly follow Rebus whereabouts within the town… The title of the book is taken from a song of Jackie Leven, a reminder that music is always an essential element in Rankin’s book, as Rebus’ tastes seem to mimic Rankin’s (or vice-versa). A definitely great title… And great cover.

Saints of the Shadow (Bible) is as usual always in tune with the current events in Scotland, from the campaigns for and against independence, to the roadwork for the new tram (which opened two days prior to my arrival in the city). Reminding me of Set in Darkness, set around the building of the then new Scottish parliament. This book is a good serving of Rebus, albeit in a sort of schadenfreunde way, as the (DI demoted to DS) Rebus is irresistibly getting close to retirement, cannot fight or drink so much or even impose his views upon his colleagues, even the most inclined towards him… So (spoiler!) the fight between Rebus and Fox, forced to work together, that I was expecting does not really take place. On the opposite, the earlier attempts of Fox to frame Rebus for his “bad-cop” attitude have vanished and (re-spoiler!) Rebus is central to framing some of his earliest colleagues from Summerhall, even though the book maintains the ambiguity for a long while. As often in detective stories, too many coincidences mar the credibility of the story, which is centred around a few characters and with much less of a societal or political framework than in earlier volumes. Maybe the most interesting character in Saints of the Shadow (Bible) is Siobhan Clarke, as she is growing in stature and authority, breaking the close partnership with Rebus while preserving the deep friendship. (As mentioned in the previous review, I do think Rankin should “finish” Rebus’ cycle and move to another theme and style, but, provisional on this, an enjoyable read completing “the” Scottish experience!))

standing in another man’s grave

Posted in Books, Mountains, Travel with tags , , , , , , on July 13, 2013 by xi'an

“Just another night when he would not quite make it as far as the bedroom.” Standing in another man’s grave

Rebus is back indeed! When my friend Arnaud told me there was a new Rebus, I could not believe it: I thought Rankin had stopped the series with Rebus’ retirement, and one of the best possible endings (Rebus resuscitating his nemesis, Cafferty, and the superb title of Exit Music) to the series. Now, a new novel has appeared, Standing in another man’s grave, signifying Rebus return on the literary scene (and on the Scottish sleuthing scene as well).

“It’s an odd little country, this, isn’t it? I just mean it’s hard to fathom sometimes. I’ve lived here most of my life and I still don’t understand the place.” Standing in another man’s grave

So, a few years after his retirement (and a few years after the ‘last’ novel), Rebus reappears, as a civil assistant to a jeopardised cold case unit in Edinburgh. Unsurprisingly, Rebus cannot stay put and starts participating in a police investigation about the current disappearance of a young girl. With a possible link with earlier disappearances along the A9 road from Perth to Inverness… (A road with a surprising number of Scotch distilleries along the way, but this is a false trail!)

“A nation of 5 million huddled together as if cowed by the elements and the immensity of the landscape surrounding them, clinging to notions of community and shared history.” Standing in another man’s grave

Pretty soon, Rebus takes over the enquiry and without much backup (except from his former colleague Siobhan) figures out most of the clues leading to the thread common to those young girl disappearances. Pushing towards the resolution with means as grey and borderline as usual. Since part of the book is about Rebus trying to reapply for police work thanks to a new law and the Complaints inspector Malcom Fox is trying to prevent this, the next book (as there will be a next book!) may see Rebus in more trouble.

“Rebus began to wonder if he’d ever been further from a pub in his life.” Standing in another man’s grave

This is Rebus’ Rankin back to life and still… I had the definitive impression that Rebus had gotten much older than the few years since his “retirement”. The story starts as if he had lost all contact with former colleagues and only kept in touch with retirees and dead policemen… Even the early dialogues with Siobhan sound contrived. This may actually be intentional. The story itself has nice sides (like the use of Twitter and Facebook by young officers or the elimination of the catalyst case that started the whole story), but the resolution requires too much of a suspension of disbelief. Too many drinks. Too much driving (even though all those names of towns reminded me of places I visited or wanted to visit in Scotland). Nonetheless enjoyable and a page-turner and paving the way to The Saints of the Shadow Bible… With Scottish independence looming in the back!