# Blog Archives

May 12, 2014
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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

## terrible graph of the day

May 12, 2014
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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 the (2010)

## stopping rule impact

May 8, 2014
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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). Since time

## Le Monde puzzle [#865]

May 5, 2014
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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

## RSS statistical analytics challenge 2014

May 1, 2014
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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

## Le Monde puzzle [#869]

April 26, 2014
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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

## AISTATS 2014 / MLSS tutorial

April 25, 2014
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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

## Le Monde sans puzzle [& sans penguins]

April 11, 2014
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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

## data scientist position

April 6, 2014
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Our newly created Chaire “Economie et gestion des nouvelles données” in Paris-Dauphine, ENS Ulm, École Polytechnique and ENSAE is recruiting a data scientist starting as early as May 1, the call remaining open till the position is filled. The location is in one of the above labs in Paris, the duration for at least one

## Le Monde puzzle [#860]

April 3, 2014
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A Le Monde mathematical puzzle that connects to my awalé post of last year: For N≤18, N balls are placed in N consecutive holes. Two players, Alice and Bob, consecutively take two balls at a time provided those balls are in contiguous holes. The loser is left with orphaned balls. What is the values of