Paul R Swank wrote:
>
> Regression toward the mean occurs when the pretest is used to form the groups, which
>it appears is the case here.
Of course it "occurs": - but remember that the magnitude depends on
r^2. In the case where there is strong correlation between the pretest
and the posttest, we do not expect regression to the mean to be
particularly significant.
Now, it is generally acknowledged that there are some schools which
_consistently_ perform better than others. (If that were not the case,
nobody would be much surprised by any one school failing to meet its
goal!) Year-over-year variation for one school is presumably much less
than between-school variation.
Therefore, I would not expect regression to the mean to be sufficient
to explain the observed outcome (in which "practically no" top schools
met expectations); and I conclude that the goals may well have been
otherwise unreasonable. Indeed, requiring every school to improve its
average by at least two points every year is not maintainable in the
long run, and only justifiable in the short term if there is reason to
believe that *all* schools are underperforming.
-Robert Dawson
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