R finals

January 30, 2013

(This article was first published on Xi'an's Og » R, and kindly contributed to R-bloggers)

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

Filed under: R, Statistics, University life Tagged: accept-reject algorithm, bootstrap, India, ISBA, ks.test(), normalising constant, R exam, Université Paris-Sud, Varanasi

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