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Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , on October 3, 2021 by xi'an

significant changepoint? [poor statistics]

Posted in pictures, Statistics, Travel with tags , , , , , , , on May 5, 2021 by xi'an

A rather short-shighted item of news in Libération on road deaths rising in March 2021 for the first time since the beginning of lockdown in March 2020. The increase is by 22 persons, which is arguably not statistically significant (although terribly significant for the victims and their families) and somehow to be expected when considering the figures are averages over 12 months, hence representing the new volume of driving induced by the lockdown measures like work-at-home, closed schools, cancelled winter vacations. At best the following figures should see a plateau. More globally, this huge dip in the number of deaths, bringing us back to the 1920’s figures!,  is to be celebrated, alas with no prospect that this lower rate will resist a return to higher levels of activity.

récits du vieux royaume [book review]

Posted in Books, pictures with tags , , , , , , on April 18, 2021 by xi'an

Following my enthusiastic reading of Jaworski’s Gagner la Guerre at the start of the first lockdown last year (!), I read this March the short stories at the beginning of a single volume called Récits du Vieux Royaume, which I found even better for the care in the writing style, the originality and diversity of the stories, the strong connection with traditional folklore and with the woes and worries of rural people, some of which could have been those of my not-so-remote ancestors, the mostly subtle insertion of details on the . (The connection with role game scenarios is close to invisible here.) It is only when reaching the second half of this book that I realised it contained the book I had bought and read last year. Rather than additional jewels…

“Elle racontait des histoires anciennes, des chroniques séculaires, des légendes à demi oubliées, ensevelies dans un passé fabuleux. Elle racontait la Geste de Leodegar le Resplendissant, ses batailles, ses victoires, l’union des clans autour du jeune héros habité par le souffle d’un dieu. Elle racontait le Vieux Royaume à l’époque de sa splendeur, Chrysophée aux murailles dorées, la prospérité et l’harmonie des campagnes, les forteresses orgueilleuses des trois duchés. Aux heures froides de la nuit elle racontait parfois les heures terribles de la guerre des Grands Vassaux, les morts marchant mêlés aux vivants dans les armées de Malvern, Chrysophée incendiée dans le soir, les derniers héros de Leomance, de Kahad Burg et de Valanael, ivres d’horreur et de désespoir, livrant combat pour défendre la berge de la Listrelle..”

hands-on probability 101

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , , on April 3, 2021 by xi'an


When solving a rather simple probability question on X validated, namely the joint uniformity of the pair

(X,Y)=(A-B+\mathbb I_{A<B},C-B+\mathbb I_{C<B})

when A,B,C are iid U(0,1), I chose a rather pedestrian way and derived the joint distribution of (A-B,C-B), which turns to be made of 8 components over the (-1,1)² domain. And to conclude at the uniformity of the above, I added a hand-made picture to explain why the coverage by (X,Y) of any (red) square within (0,1)² was uniform by virtue of the symmetry between the coverage by (A-B,C-B) of four copies of the (red) square, using color tabs that were sitting on my desk..! It did not seem to convince the originator of the question, who kept answering with more questions—or worse an ever-changing question, reproduced in real time on math.stackexchange!, revealing there that said originator was tutoring an undergrad student!—but this was a light moment in a dreary final day before a new lockdown.

A is for…

Posted in Statistics with tags , , , , , on December 10, 2020 by xi'an

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