Archive for Louis Lyons

Cédric, le retour ?

Posted in Books, pictures, University life with tags , , , , , , , , , , , , , , on January 12, 2026 by xi'an

Within a non-Euclidean distance of a few issues, Le Monde and Libération both ran an interview of Cédric Villani, not truly a coïncidence since he recently published Leçons de mathématique joyeuse, a general public book on mathematics (I did not read), derived from a series of conferences he gave in Paris ten years ago. With a chapter on the best and the worst errors of (Henri) Poincaré, where he states that statistics is a late-comer in the mathematics pantheon because “it is complicated, it is even completely counter-intuitive.” However, there is very little on mathematics and research in these interviews, as the interviewers are clearly more interested in the politics of Villani, a former deputé and unsuccessful candidate for the City of Paris mayorship. Although he is now teaching in both Lyon and Rennes, since he currently lives in a nearby village that happens to be very close to my family house in Morbihan.

two, three, five, …, a million standard deviations!

Posted in Books, Statistics, University life with tags , , , , , , , on September 26, 2014 by xi'an

I first spotted Peter Coles’ great post title “Frequentism: the art of probably answering the wrong question” (a very sensible piece by the way!, and mentioning a physicist’s view on the Jeffreys-Lindley paradox I had intended to comment) and from there the following site jumping occured:

“I confess that in my early in my career as a physicist I was rather cynical about sophisticated statistical tools, being of the opinion that “if any of this makes a difference, just get more data”. That is, if you do enough experiments, the confidence level will be so high that the exact statistical treatment you use to evaluate it is irrelevant.” John Butterworth, Sept. 15, 2014

After Val Johnson‘s suggestion to move the significant level from .05 down to .005, hence roughly from 2σ up to 3σ, John Butterworth, a physicist whose book Smashing Physics just came out, discusses in The Guardian the practice of using 5σ in Physics. It is actually induced by Louis Lyons’ arXival of a recent talk with the following points (discussed below):

  1. Should we insist on the 5 sigma criterion for discovery claims?
  2. The probability of A, given B, is not the same as the probability of B, given A.
  3. The meaning of p-values.
  4. What is Wilks Theorem and when does it not apply?
  5. How should we deal with the `Look Elsewhere Effect’?
  6. Dealing with systematics such as background parametrisation.
  7. Coverage: What is it and does my method have the correct coverage?
  8. The use of p0 versus p1 plots.

Continue reading →