I think the key, John, is comparing performance records. The bright student continued on to have an excellent exam. The poor student, who was close to failing (and also happened to sit near the good student) suddenly had an astounding performance. Applying Occam's Razor here: What seems like the most likely explanation is the most likely explanation. And he/she probably couldn't see her neighbor's paper clearly enough to add the fine computation her neighbor provided, so just gave the answer.
I continue to marvel, as you and I discussed this afternoon, that all too frequently, the poor students don't realize that to suddenly turn in an almost perfect exam, or as in Carol's student's case, an excellent paper, is just TOO suspicious. Beth Benoit Granite State College Plymouth State University New Hampshire On Thu, Dec 17, 2009 at 4:00 PM, John Kulig <[email protected]> wrote: > > Yes, that time of year again! I have never used Turnitin.com but I want to > introduce another problem I just encountered ... > > Two students in stats both turned in an exam with the exact same multiple > choice answers(35 out of 39 correct, and both the correct AND incorrect > choices were identical). I have never seen this happen before. One student > was aceing the class and the other was on the verge of failing. I have a > pretty solid case of copying not just on this point on other parts of the > exam because the poorer student also had correct AND incorrect answers on > the computation part out to two decimal places (including a "proportion of > variance" effect size of 2.15 which is bogus), all without computation, just > answers written down. Because I am grading non-stop and need a diversion, I > am intrigued with guestimating the probability of the MC being identical on > all 39 given no cheating. It's obviously a low probability as my MC scores > average close to "optimal difficulty" level (in the 60 - 70% range), so it's > not the case that most people get most of them correct. > > Anybody ever try to model this problem? I can assume they both knew 35 > answers, get the frequencies of all the wrong answers for the class, and > assume people guess randomly when they don't know. But they only missed 4. I > can also regress this exam on previous exam scores and show that the poor > student getting only 4 wrong is an outlier, but that may not be convincing > enough .. and thoughts would be appreciated. > > If the student were brigher they should have changed a few answers and > scribbled a few computations here and there on the sheet! > > -------------------------- > John W. Kulig > Professor of Psychology > Plymouth State University > Plymouth NH 03264 > -------------------------- > > ----- Original Message ----- > From: "DeVolder Carol L" <[email protected]> > To: "Teaching in the Psychological Sciences (TIPS)" < > [email protected]> > Sent: Thursday, December 17, 2009 2:56:53 PM GMT -05:00 US/Canada Eastern > Subject: [tips] It's that plagiarism time of year again... > > Hi, > I have a student who has done poorly on his exams but has turned in a > stunningly good paper. Frankly, I don't think he wrote it but I'm having > difficulty showing that. I have Googled key phrases but nothing has turned > up, so I don't think he copied and pasted, I think he bought it. Can anyone > give me some idea of what Turnitin.com charges for an individual license? > It's the only thing I can think of, other than confronting the student, > which will most likely be my next step. I hate this stuff, it takes so much > time and really takes a toll on my enthusiasm for grading. > > Thanks in advance for any help you can provide. > Carol > > > > > Carol DeVolder, Ph.D. > Professor of Psychology > Chair, Department of Psychology > St. Ambrose University > Davenport, Iowa 52803 > > phone: 563-333-6482 > e-mail: [email protected] > > > > > --- > To make changes to your subscription contact: > > Bill Southerly ([email protected]) > > --- > To make changes to your subscription contact: > > Bill Southerly ([email protected]) > --- To make changes to your subscription contact: Bill Southerly ([email protected])
