Re: science for all?

[Jack Uretsky <jlu@HEP.ANL.GOV>]

On Wed, 2 Jan 2002, Jack Uretsky wrote:

> Hi John-
>         This is frustrating, because I can't see that you are dealing with
> the point that I am making.  Would you mind stating your understanding of
> my posting?
>                                         Regards,
>                                                 Jack
        John's answer, posted to me privately, leads me to the conclusion
that we are totally not communicating.  So here's a challenge to John and
Brian:

        I have set up a program to generate random pre- and post- test
scores for classes of approximately 100 students.  In the following six
cases (done in sequence with no selection), some of the pre- and post-
tests were taken from identical pre- and post- distributions (there was
no change in "student understanding" between the tests), and some from
cases where the statistical properties of the population changed
between the tests.  Tell me which cases are which; after you have done
so, I'll tell you what the statistical properties of the populations from
which the samples were drawn actually were:
                pre-test                        post-test
case     mean       SD                        mean      SD         n
1        50.9     333                         5.6      4.9       100
2         7.0      15                         5.1      1.6       101
3         5.3       3.9                       5.0      1.2       100
4         6.4       9.2                       6.1      7.3       101
5         9.7      26                         8.2     24          99
6         8.7      18                        51      432         100

                                                        Regards,
                                                          Jack