## sans sérif & sans chevron

Posted in Books, R, Statistics, University life with tags , , , , , , , , , , , , on June 17, 2020 by xi'an
{\sf df=function(x)2*pi*x-4*(x>1)*acos(1/(x+(1-x)*(x<1)))}

As I was LaTeXing a remote exam for next week, including some R code questions, I came across the apparent impossibility to use < and > symbols in the sans-sérif “\sf” font… Which is a surprise, given the ubiquity of the symbols in R and my LaTeXing books over the years. Must have always used “\tt” and “\verb” then! On the side, I tried to work with the automultiplechoice LaTeX package [which should be renamed velomultiplechoice!] of Alexis Bienvenüe, which proved a bit of a challenge as the downloadable version contained a flawed file of automultiplechoice.sty! Still managed to produce a 400 question exam with random permutations of questions and potential answers. But not looking forward the 4 or 5 hours of delivering the test on Zoom…

## Bayesian Inference, at £1400 per chapter…

Posted in Books, Statistics, University life with tags , , , , , on June 1, 2019 by xi'an

Another unsolicited email (“This is a friendly reminder that….”) from a UK operator called IntechOpen about publishing a chapter in an Open Access book about Bayesian Inference. And edited by Tang Niansheng. As detailed on the publisher page

“The aim of this book is to introduce the newly developed Bayesian methods, including Bayesian variable selection (e.g., fixed-dimensional data analysis and high/ultrahigh dimensional data analysis), Bayesian influence analysis (e.g., case deletion method and local influence analysis), Bayesian estimation and clustering methods (e.g., fixed dimensional data, high/ultrahigh dimensional data analysis, Bayesian network, and Bayesian clustering for big data), Bayesian hypothesis test including discrete and continuous random variables, variational Bayesian analysis and Bayesian clinical trials including design and dose-finding algorithm”

which is neither off the mark nor particularly innovative, as Bayesian (hand?)books go. With the slight impediment of a £1400 fee per chapter. Even at the current exchange rate, this is far from “free of charge” (which only applies to the book being “free to download, read and share”. (Given the on-going upheavals of UK politics, it may soon become affordable, though!)

## estimation exam [best of]

Posted in Books, Kids, Statistics with tags , , , , , , , , on January 29, 2019 by xi'an

Yesterday, I received a few copies of our CRC Press Handbook of Mixture Analysis, while grading my mathematical statistics exam 160 copies. Among the few goodies, I noticed the always popular magical equality

E[1/T]=1/E[T]

that must have been used in so many homeworks and exam handouts by now that it should become a folk theorem. More innovative is the argument that E[1/min{X¹,X²,…}] does not exist for iid U(0,θ) because it is the minimum and thus is the only one among the order statistics with the ability to touch zero. Another universal shortcut was the completeness conclusion that when the integral

$\int_0^\theta \varphi(x) x^k \text{d}x$

was zero for all θ’s then φ had to be equal to zero with no further argument (only one student thought to take the derivative). Plus a growing inability in the cohort to differentiate even simple functions… (At least, most students got the bootstrap right, as exemplified by their R code.) And three stars to the student who thought of completely gluing his anonymisation tag, on every one of his five sheets!, making identification indeed impossible, except by elimination of the 159 other names.

## local package delays

Posted in Books, R, Statistics with tags , , , , , , , , on January 25, 2013 by xi'an

When Jean-Michel and I left Berlin, a month ago, I really thought we were that close to sending the new edition of Bayesian Core. Alas, we are not done yet for a series of reasons: leaving for India did not give me enough time to complete the help manual, some codes from the original version did not seem to work any longer, apparently jeopardising a whole chapter!, and the package did not seem to compile. Yesterday, we met again and made progress that makes me much more confident. For one thing, the R code that “did not work” was an original spreadsheet of Bayesian Core that we turned into functions towards the completion of the bayess package. However, due to sloppy programming at the time, we had used global variables that were called inside functions without being (explicitly) declared as variables. When those R codes got turned into functions, variables defined inside those functions were no longer global and recognised by the other functions defined within those same functions… Silly me! Once this issue got spotted by Jean-Michel, as well as the use of a few && instead of &’s, the whole problem unravelled rather quickly and we got a compiled package by the end of the day, even though some of the demos (reproducing the outcome found in the text) are still bugged. Stay tuned!

## “Introducing Monte Carlo Methods with R” is now copyedited

Posted in Books, Statistics with tags , , , , on October 12, 2009 by xi'an

On Friday, I received the annotated copy of our book Introducing Monte Carlo Methods with R with George Casella, from Springer Verlag. This means that a copy-editor went in a few weeks through the book, checking for consistency in the notations, the style and the spelling, correcting for the few typos and awkward sentences, and tracking all references. I always find this experience interesting in that it measures how far I am from writing in seamless English and also because it gives a style to the book. Going through the first chapters yesterday, I noticed some idiosyncrasies of the copyeditor: moving most “like” to “such as” and many “that” to “which”, all “situation when” to “situation where”,  as well as inverting the location of “above” from adjective to adverb… An interesting fluctuation among copyeditors is whether or not “to allow” is systematically followed by “for”, the current one being closer to the French way of turning “to allow” into a transitive verb. The most frustrating part is the seemingly random removals and additions of comas! And repeated comments that show those copyeditors have no knowledge of LaTeX. But, overall, I am, as always, quite impressed by the quality of the work of those copyeditors who often spend time to explain in the margin why they suggest a particular change, such as why we should write “first four bits” instead of “four first bits”.: there only is one first bit… (I still remember the copyeditor of The Bayesian Choice who went to the extent of retranslating awkward sentences into French to try to understand my meaning!)

I hope to be done with this last correction within a few days am now done with this last correction after two days of non-stop typing and this will be the last and final step before the book goes to production.  Yesss!!! We should soon get a cover and a publication date (March 1, 2010?). Of course, typos will remain (I found three yesterday in the two first chapters) but given that Springer Verlag is now operating a print-on-demand policy, correcting for those typos will be feasible on a continuous basis.