Sceaux snapshot [jatp]

Posted in Statistics with tags , , , , , , on April 22, 2018 by xi'an

X de Sceaux 2018 [20:25, 14/185, 2/21]

Posted in Kids, Running with tags , , , , , on February 15, 2018 by xi'an

Without any preparation [apart from my daily jog], I signed for the 5k in my local park, two days before the race, the 43rd trail of Sceaux. As it had snowed a lot in the past week, the race was mostly on (in?) slush, if not overly slippery, the remaining part being enjoyably muddy! I did a fairly poor time but still managed to squeeze in between the first and the third runners in my V2 (Grand Masters) category. With a 4 seconds differential each time!

complex Cauchys

Posted in Books, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , on February 8, 2018 by xi'an

During a visit of Don Fraser and Nancy Reid to Paris-Dauphine where Nancy gave a nice introduction to confidence distributions, Don pointed out to me a 1992 paper by Peter McCullagh on the Cauchy distribution. Following my recent foray into the estimation of the Cauchy location parameter. Among several most interesting aspects of the Cauchy, Peter re-expressed the density of a Cauchy C(θ¹,θ²) as

f(x;θ¹,θ²) = |θ²| / |x-θ|²

when θ=θ¹+ιθ² [a complex number on the half-plane]. Denoting the Cauchy C(θ¹,θ²) as Cauchy C(θ), the property that the ratio aX+b/cX+d follows a Cauchy for all real numbers a,b,c,d,

C(aθ+b/cθ+d)

[when X is C(θ)] follows rather readily. But then comes the remark that

“those properties follow immediately from the definition of the Cauchy as the ratio of two correlated normals with zero mean.”

which seems to relate to the conjecture solved by Natesh Pillai and Xiao-Li Meng a few years ago. But the fact that  a ratio of two correlated centred Normals is Cauchy is actually known at least from the1930’s, as shown by Feller (1930, Biometrika) and Geary (1930, JRSS B).

Solstice [Blanca Li dance company]

Posted in pictures with tags , , , , , on November 1, 2017 by xi'an

Yesterday night, we went to watch a [contemporary] dance show entitled Solstice in the nearby Les Gémeaux theatre. (With real tickets this time!) As I had no notion of what the show was about, it came as a massive shock, from the design of the scene, sitting under a white cloud that turns to fog or to waves, to the powerful soundtrack, oscillating between industrial music and Western Africa djembe and kora, including a scene with percussions made of hitting water, to impressive dancers, conveying vividly different stages of life and death and communion with or rejection from nature… The final scenes involving a dark sand that could substitute for water, pollution, or just the sand of a fighting arena, were particularly strong and moving. But so were those in a recreated tempest, with a stunning video background. Brilliant!

end of my dream! [aka no free lunch]

Posted in pictures with tags , , , , , , , on October 21, 2017 by xi'an

In June, last June, I received a collection of nominal tickets for the National Theatre next door, Les Gémeaux, which animates a rich and diverse scene, attracting to my suburb spectators from all over Paris. Scene that I do not attend as much as I would like, except for a few contemporary dance shows now and then… As I had not ordered these tickets, I was rather pleasantly surprised and wondered at the source of this princely gift, ruling out close family and anonymous sponsors! And the size of it was way too much for a commercial teaser. The most likely explanation was thus a mistake send to the wrong X. Nonetheless, being at home for the first concert, I went to check whether or not my allotted seats were occupied. And unsurprisingly they were. (I did not push the cheek as far as engaging into a discussion with my homonym!) Missing an Austrian theme with Mozart and Haydn. (But I have regular tickets for ext weekend!)