Archive for the Running Category

zurück nach Wien

Posted in Statistics, University life, Running, Wines, Travel, pictures with tags , , , , , , , , on September 16, 2017 by xi'an

Today, I am travelling to Vienna for a few days, primarily for assessing a grant renewal for a research consortium federating most Austrian research groups on a topic for which Austria is a world-leader. (Sorry for being cryptic but I am unsure how much I can disclose about this assessment!) And taking advantage on being in Vienna, for a two-day editing session with Sylvia Früwirth-Schnatter and Gilles Celeux on our Handbook of mixtures analysis project. Which started a few years ago with another meeting in Vienna. And taking further advantage on being in Vienna, for an evening at the Volksoper, conveniently playing Die Zauberflöte!

wanton and furious cycling

Posted in pictures, Running, Travel with tags , , , , , , , , on September 10, 2017 by xi'an

A cyclist was convicted of “wanton or furious driving” last week in London after hitting a pedestrian crossing the street, leading to her death a few days later. The main legal argument for the conviction was that the cyclist was riding a “fixie”,  a bike with no front brake and fixed-gear, as used in track cycling. Which is illegal in Britain and, I just found out, in France too. (He was actually facing manslaughter, for which he got acquitted.) This is a most tragic accident, alas leading to a loss of a human life, and I did not look at the specifics, but I do not get the argument about the brakes and the furious driving: if the rider was going at about 28 km/h, which seems a reasonable speed in low density areas [and is just above my average speed in suburban Paris], and if the pedestrian stepped in his path six meters ahead, he had less than a second to react. Front brake or not, I am certainly unable to react and stop in this interval. And braking hard with the front brake will invariably lead to going over the bars: happens to me every time I have to stop for a car with my road bike. And would if I had to stop for a pedestrian.

Incidentally [or accidentally], here is the item of British Law from 1861 on which prosecution was based:

“Whosoever, having the charge of any carriage or vehicle, shall by wanton or furious driving or racing, or other wilful misconduct, or by wilful neglect, do or cause to be done any bodily harm to any person whatsoever, shall be guilty of a misdemeanour, and being convicted thereof shall be liable, at the discretion of the court, to be imprisoned for any term not exceeding two years.”

And here are the most reasonable views of the former Olympian Chris Boardman on this affair and the hysteria it created…

Milano street-art [jatp]

Posted in Kids, pictures, Running, Travel with tags , , , , on September 9, 2017 by xi'an

slow food all’italiani

Posted in pictures, Running, Statistics, Travel, Wines with tags , , , , , , , on September 3, 2017 by xi'an

how many academics does it take to change… a p-value threshold?

Posted in Books, pictures, Running, Statistics, Travel with tags , , , , , , , , on August 22, 2017 by xi'an

“…a critical mass of researchers now endorse this change.”

The answer to the lightpulp question seems to be 72: Andrew sent me a short paper recently PsyarXived and to appear in Nature Human Behaviour following on the .005 not .05 tune we criticised in PNAS a while ago. (Actually a very short paper once the names and affiliations of all authors are taken away.) With indeed 72 authors, many of them my Bayesian friends! I figure the mass signature is aimed at convincing users of p-values of a consensus among statisticians. Or a “critical mass” as stated in the note. On the next week, Nature had an entry on this proposal. (With a survey on whether the p-value threshold should change!)

The argument therein [and hence my reservations] is about the same as in Val Johnson’s original PNAS paper, namely that .005 should become the reference cutoff when using p-values for discovering new effects. The tone of the note is mostly Bayesian in that it defends the Bayes factor as a better alternative I would call the b-value. And produces graphs that relate p-values to some minimax Bayes factors. In the simplest possible case of testing for the nullity of a normal mean. Which I do not think is particularly convincing when considering more realistic settings with (many) nuisance parameters and possible latent variables where numerical answers diverge between p-values and [an infinity of] b-values. And of course the unsolved issue of scaling the Bayes factor. (This without embarking anew upon a full-fledged criticism of the Bayes factor.) As usual, I am also skeptical of mentions of power, since I never truly understood the point of power, which depends on the alternative model, increasingly so with the complexity of this alternative. As argued in our letter to PNAS, the central issue that this proposal fails to address is the urgency in abandoning the notion [indoctrinated in generations of students that a single quantity and a single bound are the answers to testing issues. Changing the bound sounds like suggesting to paint afresh a building on the verge of collapsing.

maggiore alba [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , on August 17, 2017 by xi'an

Skye window [jatp]

Posted in Mountains, pictures, Running, Statistics, Travel with tags , , , , , , , on August 12, 2017 by xi'an