From owner-cse191-sp08-list@LISTSERV.BUFFALO.EDU Tue Mar 4 10:58:47 2008 Date: Tue, 4 Mar 2008 10:58:20 -0500 From: "William J. Rapaport" Subject: 191: Midterm Exam statistics To: CSE191-SP08-LIST@LISTSERV.BUFFALO.EDU ------------------------------------------------------------------------ Subject: 191: Midterm Exam statistics ------------------------------------------------------------------------ Here are some statistics on the midterm exam. None of the numbers below include the extra-credit question; more on that later. Also, none of the numbers below include the 0s given to students who did not take the exam. Total possible points = 189 Grade ranges and averages: raw scores: 60-189 = D-A average: 129 = C+ To see the distribution of grades, link to: http://www.cse.buffalo.edu/~rapaport/191/S08/191MT-sortedbyletter.htm On that chart, I show the distribution for all letter grades as well as the distribution for all A's (A, A-), all Bs (B+,B,B-), etc. (these are indicated in the bottom chart by lower-case letters). You'll note that both curves are nearly normal distributions, slightly skewed on the high side. As for the extra-credit question, only a few of you tried it, and no one trying it got full credit. It raised the average raw score only to 130, and did increase a few students' grades one-third of a letter grade (e.g., B became B+, etc.). ------------------------------------------------------------------------ The biggest thing I noticed was the large number of students, approximately the same number as those who don't attend lecture :-), who did not have the foggiest idea how to represent an English sentence in FOPL or how to even begin to prove a theorem. For example, I could easily distinguish between: * students who knew what they were doing (even if they only got partial credit on a problem); such a student might get the problem right or might err in the following way: e.g., representing "all dogs are animals" as: Ax[Dog(x) ^ Animal(x)] which is semantically INcorrect (it means that everything is both a dog and an animal!), but at least is syntactically correct * students who had a vague idea of what they were doing but got the problems completely wrong; such a student might have represented "all dogs are animals" as: D -> A which isn't even FOPL (it's propositional logic, sort of) * and students who seemed completely clueless; many students did something analogous to representing "all dogs are animals" as: m + n = even which doesn't even make sense mathematically. It's clear that that last group of students (who tended to get Ds or low Cs on the midterm) are not attending lecture, not reading the text, and/or not doing more than the bare minimum (if that) in the course. Fair warning: the course gets harder as the semester progresses! ------------------------------------------------------------------------ Although I know that many of you would have liked more time to work on the exam, I am satisfied that those of you who are studying are doing well and that those of you who are not doing as well as you might like can easily do better. You will have plenty of opportunity to improve your grades during the rest of the semester via HWs and the final exam. In addition, I will make the following offer: If your final-exam grade is higher than your midterm grade, then I will replace your midterm grade in the final grade computation by your final-exam grade. From owner-cse191-sp08-list@LISTSERV.BUFFALO.EDU Tue Mar 4 12:38:23 2008 Date: Tue, 4 Mar 2008 12:38:03 -0500 From: "William J. Rapaport" Subject: 191 Mid Term Grades To: CSE191-SP08-LIST@LISTSERV.BUFFALO.EDU I apologize for a computer glitch that briefly publicized all of your grades. That file has been deleted. I will try again to post the overall statistics. From owner-cse191-sp08-list@LISTSERV.BUFFALO.EDU Tue Mar 4 12:50:02 2008 Date: Tue, 4 Mar 2008 12:48:59 -0500 From: "William J. Rapaport" Subject: 191: Corrected website for Midterm exam grade summary To: CSE191-SP08-LIST@LISTSERV.BUFFALO.EDU ------------------------------------------------------------------------ Subject: 191: Corrected website for Midterm exam grade summary ------------------------------------------------------------------------ Here is the correct URL for a chart showing the summary grades. There are two charts: One showing the distribution of letter grades (A, A-, ..., D) and the other showing the distribution of letter grades ignoring +/- (a,b,c,d), where a = {x | x = A v x = A-} b = {x | x = B+ v x = B v x = B-}, etc. http://www.cse.buffalo.edu/~rapaport/191/S08/191MT-summary.htm Once again, I apologize for posting the wrong file, and I thank those students who called the error to my attention.