Stan Brown wrote:
> Another instructor and I gave the same exam to our sections of a
> course. Here's a summary of the results:
>
> Section A: n=20, mean=56.1, median=52.5, standard dev=20.1
> Section B: n=23 mean=73.0, median=70.0, standard dev=21.6
>
> Now, they certainly _look_ different. (If it's of any valid I can
> post the 20+23 raw data.) If I treat them as samples of two
> populations -- which I'm not at all sure is valid -- I can compute
> 90% confidence intervals as follows:
>
> Class A: 48.3 < mu < 63.8
> Class B: 65.4 < mu < 80.9
>
> As I say, I have major qualms about whether this computation means
> anything. So let me pose my question: given the two sets of results
> shown earlier, _is_ there a valid statistical method to say whether
> one class really is learning the subject better than the other, and
> by how much?
Before you jump out of a window, you should ask yourself if there
is any reason to suspect that the samples should be homogeneous
(assuming equal learning). Remember that the students are often
self-selected into the sections, and the reasons for selecting one
section over the other may well be correlated with learning styles
and/or scholastic achievements.
-------------------------------------------------------
gus gassmann ([EMAIL PROTECTED])
"When in doubt, travel."
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