CS 561: Fall 2004, About Test #2
There were 43 tests in all; 8 of you chose to do the extra credit
problem 5 in lieu of the regular problem 3. Sadly, a few tests were
little more than downloads from the web, without so much as a reference.
The high score was 100 (congratulations!); the low score, however,
was only 15; the median was 57; a passing score was around 65.
The distribution of scores is shown below.
Range Number of scores in range
----------------------------------
90-100 4
80- 89 5
70- 79 4
60- 69 8
50- 59 6
40- 49 7
30- 39 5
20- 29 2
10- 19 2
Overall, the scores in this test were more bimodal than on the
first test -- basically sorting the class into a pass group
and a fail group, of roughly equal sizes.
Since some of you who failed had already failed or dropped before,
you should take the undergraduate class in algorithms and data structures
offered this Spring 2005 semester in preparation for a last attempt
at passing the class in Fall 2005.
Some general remarks about the class:
-
Proofs are clearly a problem for many students -- I received "proofs" by example
as well as "proofs" by repetition (restate the conclusion many times with
slight variations), neither one of which categories has anything to do with
mathematical or even handwaving proofs. Thus Problem #1 got some of the
worst scores on the test, even though it was probably the simplest of the
four problems.
-
Too many students still do not appear to realize that an algorithm without
a proof of correctness (however informal) is worthless. I generally gave
half credit for a correct algorithm without any correctness argument;
but I occasionally gave more when the presentation of the algorithm
includes hints as to the reason it solves the problem and occasionally less
when the attempt at proof shows that the writer did not really understand
the algorithm. This lack is the reason why so many students lost points
on Problem #2: although just about everybody figured out that topological
sort was the solution, relatively few actually showed why.
-
Many of you copied from articles on the web and in textbooks without
any attribution. Once again, this is academic dishonesty, no different
than copying from a fellow student: you are attempting to pass somebody
else's work as your own. Do this once in your professional career and
you are lost forever.
Distribution of semester grades:
A+ 1
A 2
A- 2
B+ 1
B 2
B- 4
C+ 1
C 11
F 16
I 4
W/WP 4