R finals

From my office in Dauphine, on the hottest day of the year (so far)...On the morning I returned from Varanasi and the ISBA meeting there, I had to give my R final exam (along with three of my colleagues in Paris-Dauphine). This year, the R course was completely in English, exam included, which means I can post it here as it may attract more interest than the French examens of past years…

I just completed grading my 32 copies, all from exam A, which takes a while as I have to check (and sometimes recover) the R code, and often to correct the obvious mistakes to see if the deeper understanding of the concepts is there. This year student cohort is surprisingly homogeneous: I did not spot any of the horrors I may have mentioned in previous posts.

I must alas acknowledge a grievous typo in the version of Exam B that was used the day of the final: cutting-and-pasting from A to B, I forgot to change the parameters in Exercise 2, asking them to simulate a Gamma(0,1). It is only after half an hour that a bright student pointed out the impossibility… We had tested the exams prior to printing them but this somehow escaped the four of us!

Now, as I was entering my grades into the global spreadsheet, I noticed a perfect… lack of correlation between those and the grades at the midterm exam. I wonder what that means: I could be grading at random, the levels in November and in January could be uncorrelated, some students could have cheated in November and others in January, student’s names or file names got mixed up, …? A rather surprising outcome!

grades of some of my students at the midterm and finals R exams

6 Responses to “R finals”

  1. A more worrying issue is that a few (very few) students lost their file(s) at the end of the exam and that it took an enormous effort for our computer engineers to recover those. I wonder how we could avoid those difficulties while keeping anonymous accounts. Going around all machines at the end of the exam with USB keys is definitely a solution, but a wee pedestrian unless we enlist all of our graduate students to help us…!

  2. A great example for the importance of sanity checks.
    I’m glad you eventually got the correct file :)

  3. I actually got an email from the secretary who sent me the file with the grades that the mid-term grades were not the ones she had on her machine, so this makes much more sense!!! There must have been some confusion when handling this file, somewhere, somehow.

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