Archive for the Running Category

the (expected) demise of the Bayes factor [#2]

Posted in Books, Kids, pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , on July 1, 2015 by xi'an

AmsterXXFollowing my earlier comments on Alexander Ly, Josine Verhagen, and Eric-Jan Wagenmakers, from Amsterdam, Joris Mulder, a special issue editor of the Journal of Mathematical Psychology, kindly asked me for a written discussion of that paper, discussion that I wrote last week and arXived this weekend. Besides the above comments on ToP, this discussion contains some of my usual arguments against the use of the Bayes factor as well as a short introduction to our recent proposal via mixtures. Short introduction as I had to restrain myself from reproducing the arguments in the original paper, for fear it would jeopardize its chances of getting published and, who knows?, discussed.

Statistics month in Marseilles (CIRM)

Posted in Books, Kids, Mountains, pictures, Running, Statistics, Travel, University life, Wines with tags , , , , , , , , , , , , , , on June 24, 2015 by xi'an

Calanque de Morgiou, Marseille, July 7, 2010Next February, the fabulous Centre International de Recherche en Mathématiques (CIRM) in Marseilles, France, will hold a Statistics month, with the following programme over five weeks

Each week will see minicourses of a few hours (2-3) and advanced talks, leaving time for interactions and collaborations. (I will give one of those minicourses on Bayesian foundations.) The scientific organisers of the B’ week are Gilles Celeux and Nicolas Chopin.

The CIRM is a wonderful meeting place, in the mountains between Marseilles and Cassis, with many trails to walk and run, and hundreds of fantastic climbing routes in the Calanques at all levels. (In February, the sea is too cold to contemplate swimming. The good side is that it is not too warm to climb and the risk of bush fire is very low!) We stayed there with Jean-Michel Marin a few years ago when preparing Bayesian Essentials. The maths and stats library is well-provided, with permanent access for quiet working sessions. This is the French version of the equally fantastic German Mathematik Forschungsinstitut Oberwolfach. There will be financial support available from the supporting societies and research bodies, at least for young participants and the costs if any are low, for excellent food and excellent lodging. Definitely not a scam conference!

La Rochambelle 2015 [10K – 38:28 – 73th & 4th V4]

Posted in Kids, pictures, Running, Travel with tags , , , , , , , , , on June 21, 2015 by xi'an

stade1Another year attending La Rochambelle, the massive women-only race or walk against breast cancer in Caen, Normandy! With the fantastic vision of 20,000 runners in the same pink tee-shirt swarming down-town Caen and the arrival stadium. Which made it quite hard to spot my three relatives in the race! I also ran my fourth iteration of the 10k the next day, from the British War Cemetery of Cambes-en-Plaine to the Memorial for Peace in Caen. The conditions were not as optimal as last year, especially in terms of wind, and I lost one minute on my total time, as well as one position, the third V2 remaining tantalisingly a dozen meters in front of me till the end of the race. A mix of too light trainings, travel fatigue and psychological conviction I was going to end up fourth! Here are my split times, with a very fast start that showed up in the second half near 4mn/km, when the third V2 passed me.

cambes

midnight sun [minus 50mn]

Posted in pictures, Running, Travel with tags , , , , , , on June 15, 2015 by xi'an

moon2

Móskarðshnjúkar [hiking near Reykjavik]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , on June 7, 2015 by xi'an

moskard1Today, as I had a free day (with 24 hour daylight!) in Reykjavik before the NBBC15 conference started, thanks to the crazy schedules of the low cost sister of Air France, Transavia (!), I went in search of a hike… Which is not very difficult in Iceland! moskard2I had originally planned to stop near Geysir as the dirt road beyond Gullfoss is off-limit for rental cars. Especially small 2WD like mine.

As I was driving the first kms of the Þingvellir road, I admired the Esjan range starting with the Esja mountain that we had climbed during our previous visit to Iceland. Especially the “last” peak that glowed with a warm yellow (and apparently no snow at all). More especially, because it had a top reminding me of the Old Man of Storr on its slope. (Not that I could spot it while driving!) And quickly decided this was a great opportunity for a nice hikemoskard4 and a minimum of driving as I was about 20 mn from down-town Reykjavik.

I thus took a dirt road that seemed to get closer to my goal and after 500m came to a farm yard where I parked the car and went hiking, aiming at this peak,  which name is Móskarðshnjúkar. Despite a big cut due to a torrent after the first hill, I managed to keep enough to high ground not to loose any altitude and sticking to the side of the ski station Skálafellmoskard5 (where a few people were still skiing with the noisy help of two snowmobiles), I crossed the brook easily as it was covered by snow and started moving to steeper if manageable slopes. I moskard6reached the bottom of the main peak rather quickly and then understood both its colour and the absence of snow.

As maybe visible from some of my pictures (?), the Móskarðshnjúkar peak is covered with gravel in a bright yellow stone that seems to accumulate heat very well. Climbing stramoskard3ight on the loose gravel was then impossible and I had to zigzag mostly up, trying to not lose too much ground to micro-avalanches. As I reached the tor I spotted two hikers above me and when I reached the top I realised there was a path coming from the west, connecting this peak with its neighbours. The normal route seems to come from a gravel road that starts close to Mount Esja, to the west, and as I followed the path down to the saddle between Móskarðshnjúkar and the rest of the range, I saw this path winding down to the valley with further hikers coming up. Before I crossed them, I went up again to the next peak, which was an easy if beautiful ridge walk, with moskard7still a fair amount of snow remaining on the north face (heavy enough to bear tracks of snowmobiles!). After following the ridge track for a while, it branched north to reach the main Esja plateau and I left the track to get down a rocky shoulder towards my starting point. However, I had forgotten about the torrent cut between the two ranges and this forced me to take a further detour. And to cross the torrent barefooted, as there was no stone ford on this off-path section. No big drama as the melted snow water was not that cold…

moskard8A last sight was provided by the final rocky outcrop, which enjoyed basaltic volcanic columns as on the picture above. A terrific hiking half-day with a sharp sunny weather and not too much wind except at the top. It was very pleasant to walk part of the way on moss and last year grass, with a surprising absence of bogs and mud when compared with Scotland.

Valencia snapshot [#2]

Posted in Kids, pictures, Running, Travel with tags , , , , on June 5, 2015 by xi'an

vale4

O’Bayes 2015 [day #2]

Posted in pictures, Running, Statistics, Travel, University life, Wines with tags , , , , , , on June 4, 2015 by xi'an

vale1This morning was the most special time of the conference in that we celebrated Susie Bayarri‘s contributions and life together with members of her family. Jim gave a great introduction that went over Susie’s numerous papers and the impact they had in Statistics and outside Statistics. As well as her recognised (and unsurprising if you knew her) expertise in wine and food! The three talks in that morning were covering some of the domains within Susie’s fundamental contributions and delivered by former students of her: model assessment through various types of predictive p-values by Maria Eugenia Castellanos, Bayesian model selection by Anabel Forte, and computer models by Rui Paulo, all talks that translated quite accurately the extent of Susie’s contributions… In a very nice initiative, the organisers had also set a wine tasting break (at 10am!) around two vintages that Susie had reviewed in the past years [with reviews to show up soon in the Wines section of the ‘Og!]

The talks of the afternoon session were by Jean-Bernard (JB) Salomond about a new proposal to handle embedded hypotheses in a non-parametric framework and by James Scott about false discovery rates for neuroimaging. Despite the severe theoretical framework behind the proposal, JB managed a superb presentation that mostly focussed on the intuition for using the smoothed (or approximative) version of the null hypothesis. (A flavour of ABC, somehow?!) Also kudos to JB for perpetuating my tradition of starting sections with unrelated pictures. James’ topic was more practical Bayes or pragmatic Bayes than objective Bayes in that he analysed a large fMRI experiment on spatial working memory, introducing a spatial pattern that led to a complex penalised Lasso-like optimisation. The data was actually an fMRI of the brain of Russell Poldrack, one of James’ coauthors on that paper.

The (sole) poster session was on the evening with a diverse range of exciting topics—including three where I was a co-author, by Clara Grazian, Kaniav Kamary, and Kerrie Mengersen—but it was alas too short or I was alas too slow to complete the tour before it ended! In retrospect we could have broken it into two sessions since Wednesday evening is a free evening.

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