Some subscribers to Phys-L might be interested in a recent post "The
Ceiling Effect #2" [Hake (2011)]. The abstract reads:
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ABSTRACT: Sheila Tobias (2010) in a recent APS News "Back Page"
editorial "Teachers in the Crosshairs. . .": wrote:
"In Houston, where a new value-added formula is being used to grade
teachers' skills, 'N.Y. Times' education writer Sam Dillon found a
high school physics teacher out of the running for high bonuses
because, as she reported, 'My kids come in at a very high level of
competence, scoring well before the semester begins.' After she
teaches them for a year, they continue to score well on a state
science test but show less measurable 'gain' than other classes, so
her bonus is small compared with those of other teachers. The teacher
has invented a term of her own to characterize this distortion. She
calls it the 'ceiling effect.' We might call it a saturation effect."
It's unfortunate that the teacher's bonus assigners were not aware
that it's the "average normalized gain" <g> = (<%post> - <%pre>) /
(100% - <%pre>) [the angle brackets <. . . > indicate class
averages], often used in physics education research, that can (in
some cases) be used as a gauge of relative course effectiveness, NOT
the absolute average gain <G> = (<%post> - <%pre>).
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REFERENCES [URL's shortened by <http://bit.ly/> and accessed on 12 Jan 2010.]
Hake, R.R. 2011. "The Ceiling Effect #2" online on the OPEN! AERA-L
archives at <http://bit.ly/hUnHZe>. Post of 12 Jan 2011 16:19:49-0800
to AERA-L and Net-Gold. The abstract and link to the complete post
are being transmitted to various discussion lists are also online on
my blog "Hake'sEdStuff" at <http://bit.ly/gLWr7W> with a provision
for comments.
Tobias, S. 2010. "Teachers in the Crosshairs: The Impact of 'School
Choice,' 'Reform,' and 'Accountability'," APS News 20(1), January;
online at <http://bit.ly/fc6jEj>.