Category: Kids

and it only gets worse…

” A recent survey by Bankrate.com found that just 40% of US households have enough money to cover a $1,000 in emergency expenses.” The Guardian, Feb 2, 2019 ““Until we heard those cheers coming from Albany, we thought states were moving beyond such barbaric practices.” Mr. Pence offered his argument as a litmus test of […]

simulation fodder for future exams

Here are two nice exercises for a future simulation exam, seen and solved on X validated.The first one is about simulating a Gibbs sampler associated with the joint target exp{-|x|-|y|-a(y-x|} defined over IR² for a≥0 (or possibly a>-1). The conditionals are identical and non-standard, but a simple bound on the conditional density is the corresponding […]

Le Monde puzzle [#1085]

A new Le Monde mathematical puzzle in the digit category: Given 13 arbitrary relative integers chosen by Bo, Abigail can select any subset of them to be drifted by plus or minus one by Bo, repeatedly until Abigail reaches the largest possible number N of multiples of 5. What is the minimal possible value of […]

Le Monde puzzle [#1085]

A new Le Monde mathematical puzzle in the digit category: Given 13 arbitrary relative integers chosen by Bo, Abigail can select any subset of them to be drifted by plus or minus one by Bo, repeatedly until Abigail reaches the largest possible number N of multiples of 5. What is the minimal possible value of […]

Fisher’s lost information

After a post on X validated and a good discussion at work, I came to the conclusion [after many years of sweeping the puzzle under the carpet] that the (a?) Fisher information obtained for the Uniform distribution U(0,θ) as θ⁻¹ is meaningless. Indeed, there are many arguments: The lack of derivability of the indicator function […]

revisiting marginalisation paradoxes [Bayesian reads #1]

As a reading suggestion for my (last) OxWaSP Bayesian course at Oxford, I included the classic 1973 Marginalisation paradoxes by Phil Dawid, Mervyn Stone [whom I met when visiting UCL in 1992 since he was sharing an office with my friend Costas Goutis], and Jim Zidek. Paper that also appears in my (recent) slides as […]

Le Monde puzzle [#1083]

A Le Monde mathematical puzzle that seems hard to solve without the backup of a computer (and just simple enough to code on a flight to Montpellier): Given the number N=2,019, find a decomposition of N as a sum of non-trivial powers of integers such that (a) the number of integers in the sum is […]

efficiency and the Fréchet-Darmois-Cramèr-Rao bound

  Following some entries on X validated, and after grading a mathematical statistics exam involving Cramèr-Rao, I came to wonder at the relevance of the concept of efficiency outside [and even inside] the restricted case of unbiased estimators. The general (frequentist) version is that the variance of an estimator δ of [any transform of] θ […]

L’enfant de poussière [book review]

I read this book in French, as this was the language in which it was written and also because I was given a free copy for writing a review! This is a rather unusual book, the first volume of a series called the cycle of Syffe (where Syffe is both the main character and the […]

estimation exam [best of]

Yesterday, I received a few copies of our CRC Press Handbook of Mixture Analysis, while grading my mathematical statistics exam 135 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. […]

the adoration of the golden car

As the demonstrations by the “gilets jaunes” become a fixture of French Saturdays, the French government is gradually giving up on the reforms it had started and is in particular catering to the car [and motorbike] lobby that started the protests. The symbol itself comes from the yellow fluorescent jackets found in every car and […]

Le Monde puzzle [#1081]

A “he said-she said” Le Monde mathematical puzzle (again in the spirit of the famous Singapore high-school birthdate problem): Abigail and Corentin are both given a positive integer, a and b, such that a+b is either 19 or 20. They are asked one after the other and repeatedly if they are sure of the other’s […]

the future of conferences

The last issue of Nature for 2018 offers a stunning collection of science photographs, ten portraits of people who mattered (for the editorial board of Nature), and a collection of journalists’ entries on scientific conferences. The later point leading to interesting questioning on the future of conferences, some of which relate to earlier entries on […]

and it only gets worse…

““This is absolutely the stupidest thing ever,” said Antar Davis, 23, a former zookeeper who showed up in the elephant house on Friday to take one last look at Maharani, a 9,100-pound Asian elephant, before the zoo closed.” The New York Times, Dec 29, 2018 “The Trump administration has stopped cooperating with UN investigators over […]

Treasure Island

Just spent a wonderful hour listening to excepts from Stevenson’s Treasure Island while cooking dinner… Actually promoting a new translation (in French) in a much more colloquial version than the one I read as a child. I never get enough of this story (even though Kidnapped remains my favourite and not only mine’s!). As a […]

Le Monde puzzle [#1076]

A cheezy Le Monde mathematical puzzle : (which took me much longer to find [in the sense of locating] than to solve, as Warwick U does not get a daily delivery of the newspaper [and this is pre-Brexit!]): Take a round pizza (or a wheel of Gruyère) cut into seven identical slices and turn one […]