Archive for teaching

on-line course

Posted in Kids, pictures, Statistics, University life with tags , , , , , , , , , , , on September 4, 2020 by xi'an

Since this teaching semester is 100% on-line in Paris Dauphine for the third year students, I started last Monday to teach my statistical modelling course from my office on my computer. Using a Teams connection with the 180⁺ students,  sharing my slides or my webcam with them, and writing on a Huion drawing tablet to write on the pdf slides (or on Teams whiteboard). I found the most convenient way to write on the slides was via Xournalpp. From my end of the exchange, the class went on rather smoothly, with students interacting about the practical and contents of the course. As I have also recorded my lectures (in August), and hope the students to first go through the recordings, I will see next time how much effort they have put into assimilating the material, as the on-line class will mostly concentrate on questions and applications. I also hope to have a quick multiple choice question at the end (or beginning?) of each class, but am still fishing for an interface that would (a) handle LaTeX or MathJax (b) shuffle questions from a pool of questions so that each student gets a different question (or thinks so) and (c) store the outcome of the test. Any suggestion welcome!

error bars [reposted]

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , on March 3, 2019 by xi'an

A definitely brilliant entry on xkcd that reflects upon the infinite regress of producing error evaluations that are based on estimates. A must for the next class when I introduce error bars and confidence intervals!

I’m getting the point

Posted in Statistics with tags , , , , , , on February 14, 2019 by xi'an

A long-winded X validated discussion on the [textbook] mean-variance conjugate posterior for the Normal model left me [mildly] depressed at the point and use of answering questions on this forum. Especially as it came at the same time as a catastrophic outcome for my mathematical statistics exam.  Possibly an incentive to quit X validated as one quits smoking, although this is not the first attempt

unbiased estimators that do not exist

Posted in Statistics with tags , , , , , , , on January 21, 2019 by xi'an

When looking at questions on X validated, I came across this seemingly obvious request for an unbiased estimator of P(X=k), when X~B(n,p). Except that X is not observed but only Y~B(s,p) with s<n. Since P(X=k) is a polynomial in p, I was expecting such an unbiased estimator to exist. But it does not, for the reasons that Y only takes s+1 values and that any function of Y, including the MLE of P(X=k), has an expectation involving monomials in p of power s at most. It is actually straightforward to establish properly that the unbiased estimator does not exist. But this remains an interesting additional example of the rarity of the existence of unbiased estimators, to be saved until a future mathematical statistics exam!

p-value graffiti in the lift [jatp]

Posted in Statistics with tags , , , , , , , , on January 3, 2019 by xi'an