## R [re-]exam

Posted in Books, R, Statistics, University life with tags , , , , on March 28, 2011 by xi'an

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 found exactly duplicated R codes in another R project around Introducing Monte Carlo methods with R that was returned a few weeks ago. Meaning I will have to draft a second round exam… (As Tom commented on an earlier post, team resolution of a given problem may be a positive attitude, but in the current case one student provided an A⁺⁺ answer, while two others clearly drafted an hasty resolution from the original.) Nonetheless, do not worry, I still love [teaching] R!

## Examen

Posted in Kids, pictures, University life with tags , , on February 19, 2011 by xi'an

I was visiting Jean-Michel Marin over the past two days in order to finalise our paper on ABC model choice and I noticed this very special exam on his wall. It was a copy made by his son, who is currently learning his letters, of a true exam Jean-Michel was grading a few weeks ago. Even though the picture is over-zoomed, it is possible to identify the (correct!) resolution of the MLE of the upper bound of a uniform distribution. A very cute rendering that also qualifies as Art brut! (In the spirit of Pierre Ménard, Borges’ short story about re-creation)

## R exam

Posted in R, Statistics, University life with tags , , , on January 30, 2011 by xi'an

I spent most of my Saturday perusing R codes to check the answers written by my students to the R exam I gave two weeks ago… The outcome is mostly poor, even though some managed to solve a fair part of the long problem. Except for the few hopeless cases who visibly never wrote a single line of R code before the exam, all students have managed the basics of R programming and graphics, if not of Monte Carlo approximations or of boostrapping. One of the problems involved the distribution of a disk area and I found that half of the [third year math!] students do not know the $\pi R^2$ formula! Although I had repeatedly told them about the good training in trying to solve Le Monde puzzles (as well as checking my posts about them), only one student found the solution to puzzle #49

## The ultimate exam excuse…

Posted in R, Statistics, University life with tags , , on January 20, 2011 by xi'an

A few days after my R exam (available in French here), I received this email from the department secretary:

Pour information cet étudiant est venu me trouver jeudi soir, catastrophé car il venait de constater que son stylo “PILOT Frixion”, stylo semble-t-il recommandé par certains enseignants, ne se contentait pas d’effacer la page sur son recto mais également sur son verso, rendant ses copies illlisibles… [For your information this student came to me last Thursday night, looking devastated, as he had just discovered that his “PILOT Frixion” pen, pen that seemed to have been recommended by some teachers, did not only delete the page on its front but also on its back, making his copies unreadble]

That seems like a bad joke, I cannot believe that (a) any math teacher would recommend a special pen brand, (b) the student was using this pen for the first time, (c) he did not check his exam copy before handling it back. Maybe we could design an experiment to test how quickly the eraser goes from front to back!

## R exam postprocessing

Posted in R, University life with tags , , on February 19, 2010 by xi'an

Following my three-fold R exam of last month, I had a depressing afternoon meeting (with other faculty members) some students who had submitted R codes that were suspiciously close to other submitted R codes… In other words, it looked very  likely they had cheated. (A long-term issue with my R course, alas!) During this meeting, they actually admitted either to directly copying on their neighbour’s screen, due to the limited number of terminals that forces students to be too close to one another, or to looking at (and copying) another student’s  R code file from an earlier exam.  I used different exams but with enough of the same spirit that some of the R code could be recycled.) Besides the pain of having to turn to disciplinary action at a level where students should see the point of getting real skills towards an incoming hiring, the depressing consequence of this state of affairs is that next we will have to move to a higher level of “security” when running the R exam, which most likely means we will turn back to a pencil-and-paper exam…. A paradoxical situation when teaching a computer programming course! But unless some unlikely sponsor delivers a computer room able to handle 180 students all at once, I do not see any other solution. Suggestions?!

## R exams

Posted in R, Statistics, University life with tags , , on January 11, 2010 by xi'an

As posted yesterday, today was the day of my Exploratory Statistics exam, turned into 3 R exams because of the lack of terminals for the students to work on. (We tried to encourage students to use their own laptop but less than twenty registered…) If you happen to be interested in those exams, they are available here, there, and there. The students were supposed to download their .Rhistory file or something more elaborate onto a web depository and the usual disasters stroke, from students unable to start an R session to those erasing their history just before dowloading and everything in between. Eventually, they all got their files secured and most left whinning that it was tooo haaard… Serves them well, ha!