Dennis Roberts writes:
>
> third ... usually, "curving" means lowering the cutoffs ... that were
> established at the beginning of a course (maybe in the syllabus) .... if
> that is the case ... then there is NO statistical rationale for this ...
> simply, your "gut" feeling that not enough students are making As, Bs, etc
> ... SO, you move the cutoffs down until YOU feel comfortable ...
>
In the case of my teaching philosoply, I will have to disagree with
the above. To me, a student's grade can be expressed as
grade = function(acquired information, other variables) + error
where acquired information (information gained in this class or others)
can be expressed at any level of Bloom's taxonomy of educational
objectives (i.e., from simple recall of information all the way
to evaluation),
other variables include differences in tests from one
semester to the next, differences in presentation, etc.
and the error term might just as well be incorporated into the set
of "other variables".
I believe that the marginal function of grades and information is
positively monotonic but not necessarily first-order (does a student who
made an 80 contain twice as much information as a student who make a 40?)
Therefore I often check my grade distribution to see if it matches
my expectations. I feel that classes containing more than 60
students should contain a typical mix of good and bad students. So if my
grade distribution suddenly drops in one semester, I will try to determine
the reason and add points if I feel that the difference is a result of
variables other than changes in students' information. For small classes
this is much more complicated. Luckily, it is easier to get to know
more about each student in a small class and from that knowledge I have a
better feel for what is causing the grade distribution to be higher or
lower than my expectations.
While I do not grade on a curve, I feel that if reasons exist,it is more
valid to adjust atypical grades distributions than not to adjust them.
My reason for not grading on a curve is more for class harmony. Grading on
a curve often means taking points away from some students while adding to
others. I noticed that a class can suddenly become hostile if some
students are treated better than others. This hostile environment can be
detrimental to a class's performance also.
