Blog Archives

Le Monde puzzle [#8]

March 29, 2011
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Le Monde puzzle [#8]

Another mathematical puzzle from Le Monde that relates to a broken calculator (skipping the useless tale): Given a pair of arbitrary positive integers (x,y) a calculator can either substract the same integer from both x and y or multiply either x or y by 2. Is it always possible to obtain equal

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Time series

March 28, 2011
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Time series

(This post got published on The Statistics Forum yesterday.) The short book review section of the International Statistical Review sent me Raquel Prado’s and Mike West’s book, Time Series (Modeling, Computation, and Inference) to review. The current post is not about this specific book, but rather on why I am unsatisfied with the textbooks in

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R [re-]exam

March 27, 2011
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R [re-]exam

In what seems like an endless cuRse, I found this week I had to re-grade a dozen R exams a TA’s did not grade properly! The grades I (X) got are plotted below against those of my TA (Y). There is little connection between both gradings… As if this was not enough trouble, I also

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R-ecap [-16]

March 26, 2011
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R-ecap [-16]

This morning, I noticed that none of my R related posts had appeared on R-bloggers for the past fortnight… After investigating, this was caused by…cut-and-paste! Indeed, when advertising about the special issue of TOMACS Arnaud Doucet and I edit about Monte Carlo methods in Statistics, I copied the main parts from the pdf announcement, straight

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Le Monde puzzle [#7]

March 26, 2011
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Le Monde puzzle [#7]

The mathematical puzzle from the weekend edition of Le Monde from a few weeks ago was not too hard to solve by induction but my R code failed miserably! The puzzle was as follows: A calculator is broken in such a way that it starts by exhibiting 0, then pressing 4, 6 or 0 keeps

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MCMC with errors

March 25, 2011
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MCMC with errors

I received this email last week from Ian Langmore, a postdoc in Columbia: I’m looking for literature on a subject and can’t find it:  I have a Metropolis sampler where the acceptance probability is evaluated with some error.  This error is not simply error in evaluation of the target density.  It occurs due to the

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Typos sorted, at last!

March 23, 2011
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Typos sorted, at last!

After posting so many entries about typos in my books (making you wonder how there could be any text left!) and postponing their classification for so long, I decided on Saturday afternoon to collect those entries into a comprehensive pdf document that should be more useful for readers. I incidentally noticed that my book web-page

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One bicycle for two

March 22, 2011
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One bicycle for two

Robin showed me a mathematical puzzle today that reminded me of a story my grand-father used to tell. When he was young, he and his cousin were working in the same place and on Sundays they used to visit my great-grand-mother in another village. However, they only had one bicycle between them, so they would

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JCGS 20th anniversary

March 22, 2011
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JCGS 20th anniversary

For its 20th anniversary, JCGS offers free access to papers, including Andrew’s discussion paper Why tables are really much better than graphs. (Another serious ending for an April fool joke!) Incidentally (or rather coincidentally), I received today the great news that our Using parallel computation to improve Independent Metropolis-Hastings based estimation paper is accepted by

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Statistics forum

March 21, 2011
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Statistics forum

The ASA is launching a new blog called the Statistics Forum, managed by Andrew Gelman and to which I will periodically contribute items that may induce some amount of discussion within the community, like the first entry by Michael Lavine on testing. (Meaning I will double-post on the Og and on the Statistics Forum, if

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