Archive for RER B

X Fall²⁶ World Tour

Posted in Running, Statistics, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on September 21, 2026 by xi'an

As you may have noticed from previous entries, over the past three weeks I have been almost constantly travelling, with various but mostly large amounts of luck in my travels.

Starting with a Paris-Marseille round trip for our daughter birthday, where both trains ran on time with operational WiFi and Air conditioning (and the inevitable noisy junior passengers commuting back from their vacations).

Followed a few hours later by a Paris-Lugano round trip where again the stars aligned since the flight to Milano Malpensa was on time and landed 20mn before the only direct (flexi)bus to Lugano departed. Again in time. On the way back I had to leave right after my talk (apologies!) but got a direct (if slow) train to Milano and hopped the push via Montenapoleone (!) between two Milano metro lines to reach Milano Linate with one hour to go. On time again.

One day at home to sort various pump issues (from fixing all car injectors to replacing a drainage pump that failed to stop a massive rainstorm from entering our basement, to a flat bike tyre returning from PariSanté Campus) and then a quick weekend drive to Argentan, Normandy, for which the car managed and the traffic was surprisingly smooth for the last weekend of the national August vacation break), and where I enjoyed a long run in the woody hills, one month or so prior to the Argentan half-marathon, 30 years from my first participation. Enough time back home to cook a fresh, Norman, rhubarb preserve and off to to Durham, Northumbria, by another smooth, on-time, flight, with the small hitch of the RER B—just back from being closed for an entire month—unexpectedly finishing one station too early (and a particularly noisy family returning from one amusement park). And the same on the return, via Newcastle with a glimpse from the train of the Tyne and its iconic bridge. Reminding me of my visit there for the RSS meeting in 2013, travelling with Jim Hobert.

One more day at home and at work (teaching my first Monte Carlo class of the semester) and I was back in Charles de Gaulle airport for the flight to Tokyo Haneda. With enough time to have a second breakfast in the lounge and leave my phone on my seat!, fortunately recovered a few frantic minutes later. The flight took one hour less than expected, thanks to favourable winds, with the hitches of having no AC power plug available on the plane and no Wifi on either phone or laptop, a nuisance on a 12h day flight with a talk to polish. Going through customs at Haneda was even smoother than “usual” and I only took one wrong train on my way to Yokohama. (Which happened again the next days until I decided to stick Google map schedules, which are highly accurate and constantly updated). The only hitch of the trip was the attempt at bullet summiting Fuji-san, unsurprisingly as with most of my bullet attempts!, because the weather conditions were horrendous to the point of wardens turning people off at the entry of the Yoshida path and also to the point of inducing landslides on the unique route conducting to the 5th station. I thus got stuck there with 1600 people for a few hours until the route was reopened and the shuttle restarted, obviously with some further delays in entering the (third) bus, with more confusion and jostling than usual in Japan (but also with a large proportion of foreign hikers!). Taxis were not responding either and before the news came of the reopening I was getting worried about missing my flight! While the return saw no seamless connections and no express trains, leading to a total trip time close to 5 hours, incl. a cold soba stop at a station, I still managed to reach my Haneda hotel at check-in time and to have an intense training session on their treadmill to make up for the missing 15km and 1400⁺ climb. (Rescheduling my direct bus ticket on-line proved impossible from my phone without a local help as automated translation does not work with images.) The flight back to Paris went very smoothly by the Eastern route over the pole, with AC power (making my external battery delivered by amazon.jp fortunately superfluous since it is prohibited to use on AF flights) and Wifi running. Making my working on the paper associated with the Akaike lecture way more efficient.

la grande course du grand Paris

Posted in pictures, Running, Travel with tags , , , , , , , , , , , , on March 30, 2025 by xi'an

travel woes

Posted in Travel, University life with tags , , , , , , , , , , , , , , , , on April 29, 2024 by xi'an

On my last trip to Warwick, the local (RER) train I boarded broke on its way to the CDG airport, after hitting something in a tunnel just three stops short of the airport, with so much delay and misleading communication that I missed my flight. While a minor issue for me, since I managed to work (and blog) in an airport lounge for most of the day—where I crossed path with Numerobis—, while waiting for the only flight to B’ham, this made me to reflect anew on the very poor state of the transportation network in Paris and its suburbs, with such incidents (power failures, broken rails, vetust engines, stolen cables, idiots on the tracks, &tc., even without mentioning the strikes) more and more the norm. And to wonder at how the ancient and bursting network is going to cope with the incoming flow of visitors attending the Olympics this summer… Actually, when compared with the other cities with a fairly reasonably efficient airport connection I experienced, it remains a mystery to me why the Greater Paris conurbation—whose president, Valérie Pécresse, was apparently deemed the main culprit for our train break by an incensed fellow passenger that morning!—has kept for years postponing the construction of a dedicated rail line between the airport and central Paris, as the unpredictable and uncomfortable suburban train is not delivering the intended message to Paris visitors and their still-growing contribution to the French GNP. But with the growing public opposition to any new infrastructure, incl. trains, this is unlikely to happen!

me no savi [travel madness]

Posted in Statistics with tags , , , , , , , , on June 1, 2022 by xi'an

Today, I left home in the wee hours, after watering my tomatoes!, quite excited to join the Safe, Anytime-Valid Inference (SAVI) workshop in Eindhoven, which was taking place after two years of postponement. I alas did not check the state of the train traffic beforehand and when I reached the train station I found that part of the line to De Gaulle airport was closed, due to some control cables being stolen last night. Things quickly deteriorated as the train management in Gare du Nord was pretty inefficient, meaning that the trains would stop for five minutes at each station, and that there was no rail alternative to reach Roissy. The taxi stand was a complete mess, with no queue whatsoever, and the Parisian taxis kept true to their reputation, by refusing to take people to the airport, asking for outrageous prices (60 euros per passenger), and stopping anywhere. I almost managed to get one but he refused to take me on top of the Swede family I had directed to this stand from the RER train, and this was simply my last opportunity. Über taxis were invisible and I soon realised I could not catch my flight. Later flights were outrageously expensive and there was not train seat whatsoever till the day after, so I gave up and returned home from this trip to nowhere…

approximate Bayesian inference under informative sampling

Posted in Books, Statistics, Travel, University life with tags , , , , , , , , , on March 30, 2018 by xi'an

In the first issue of this year Biometrika, I spotted a paper with the above title, written by Wang, Kim, and Yang, and thought it was a particular case of ABC. However, when I read it on a rare metro ride to Dauphine, thanks to my hurting knee!, I got increasingly disappointed as the contents had nothing to do with ABC. The purpose of the paper was to derive a consistent and convergent posterior distribution based on a estimator of the parameter θ that is… consistent and convergent under informative sampling. Using for instance a Normal approximation to the sampling distribution of this estimator. Or to the sampling distribution of the pseudo-score function, S(θ) [which pseudo-normality reminded me of Ron Gallant’s approximations and of my comments on them]. The paper then considers a generalisation to the case of estimating equations, U(θ), which may again enjoy a Normal asymptotic distribution. Involving an object that does not make direct Bayesian sense, namely the posterior of the parameter θ given U(θ)…. (The algorithm proposed to generate from this posterior (8) is also a mystery.) Since the approach requires consistent estimators to start with and aims at reproducing frequentist coverage properties, I am thus at a loss as to why this pseudo-Bayesian framework is adopted.