Publications by xi'an
Le Monde sans puzzle [& sans penguins]
As the Le Monde mathematical puzzle of this week was a geometric one (the quadrangle ABCD is divided into two parts with the same area, &tc…) , with no clear R resolution, I chose to bypass it. In this April 3 issue, several items of interest: first, a report by Etienne Ghys on Yakov Sinaï’s Abel Prize for his work “between determinism and...
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AISTATS 2014 / MLSS tutorial
Here are the slides of the tutorial on ABC methods I gave yesterday at both AISTAST 2014 and MLSS. (I actually gave a tutorial at another MLSS a few years ago, on the pretty island of Berder in Brittany, next to Vannes.) They are definitely similar to previous talks and tutorials I delivered on this topic of ABC algorithms, with only the last par...
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Le Monde puzzle [#869]
A Le Monde mathematical puzzle once again in a Sudoku mode: In an nxn table, all integers between 1 and n appear n times. If max denotes the maximum over the numbers of different integers on all rows and columns, what is the minimum value of max when n=7? when n=11? I tried to solve it by the following R code (in a pre-breakfast mode in my Re...
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RSS statistical analytics challenge 2014
Great news! The RSS is setting a data analysis challenge this year, sponsored by the Young Statisticians Section and Research Section of the Royal Statistical Society: Details are available on the wordpress website of the Challenge. Registration is open and the Challenge goes live on Tuesday 6 May 2014 for an exciting 6 weeks competition. (A wee...
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Le Monde puzzle [#865]
A Le Monde mathematical puzzle in combinatorics: Given a permutation σ of {1,…,5}, if σ(1)=n, the n first values of σ are inverted. If the process is iterated until σ(1)=1, does this always happen and if so what is the maximal number of iterations? Solve the same question for the set {1,…,2014}. I ran the following basic R code: N=...
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stopping rule impact
Here is a question from my friend Shravan Vasishth about the consequences of using a stopping rule: Psycholinguists and psychologists often adopt the following type of data-gathering procedure: The experimenter gathers n data points, then checks for significance (p<0.05 or not). If it’s not significant, he gets more data (n more data points). ...
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terrible graph of the day
A truly terrible graph in Le Monde about overweight and obesity in the EU countries (and Switzerland). The circle presentation makes no logical sense. Countries are ordered by 2030 overweight percentages, which implies the order differs for men and women. (With a neat sexist differentiation between male and female figures.) The allocation of th...
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the Flatland paradox
Pierre Druilhet arXived a note a few days ago about the Flatland paradox (due to Stone, 1976) and his arguments against the flat prior. The paradox in this highly artificial setting is as follows: Consider a sequence θ of N independent draws from {a,b,1/a,1/b} such that N and θ are unknown; a draw followed by its inverse and this inverse ar...
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understanding complex and large industrial data (UCLID 2014)
Just received this announcement of the UCLID 2014 conference in Lancaster, July 1-2 2014: Understanding Complex and Large Industrial Data 2014, or UCLID, is a workshop which aims to provide an opportunity for academic researchers and industrial practitioners to work together and share ideas on the fast developing field of ‘big data’ analysis...
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estimation of deformations of densities
Today, Jean-Michel Loubes from Toulouse gave a seminar in Dauphine on the estimation of deformations using Wassertsein distances. This is functional data analysis, where samples from random transforms of the original density are observed towards estimating the baseline (or true) measure As a neophyte, I found the problem of interest if difficult...
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