Hi
On Fri, 3 Dec 1999, RICHARD PISACRETA wrote:
> >At 8:46 AM -0600 12/2/99, Jean Edwards wrote:
> > >Statistics (and any math for that matter) is not one of my strong points
> >but
> > >doesn't the normal curve phenomenon apply to large numbers of people?
>
> Then Paul wrote:
> >At best, and only if they're randomly sampled.
> >I would guess that a class population is both truncated and skewed.
> >I'd have trouble justifying its use in classes of less than several
> >hundred.
> >
> I agree 100% so why the hell do so many administrators want to use the data
> from classes of 40 or less, as part of evaluations.
In using course evaluations, it is the distribution of Means that
is critical. For example, to estimate what percentage of classes
have average scores lower than the current one, it helps if the
means are normally distributed. As we know from the central
limit theorem, the distribution of means can be normally
distributed independently of the distribution of y. So think of
your class as a scale and the individual students as items.
Best wishes
Jim
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James M. Clark (204) 786-9757
Department of Psychology (204) 774-4134 Fax
University of Winnipeg 4L05D
Winnipeg, Manitoba R3B 2E9 [EMAIL PROTECTED]
CANADA http://www.uwinnipeg.ca/~clark
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