regression to the mean is not necessarily appropriate when looking at
pretest scores ... and then gain or improvement ...
if we had parallel tests ... one for pre and one for post ... when nothing
happens inbetween ... then maybe so ...
please see a short summary of this scenario ... applied to grading based on
gain or improvement ... at
http://roberts.ed.psu.edu/users/droberts/5501.htm
don burrill and i wrote a short paper on this ...
those high on the pre CAN gain MORE than those low on the pre IF ...
the correlation between pre and post is decent AND, most importantly ... if
the variance on the POST is LARGER than the variance on the pre
the exact reference to the paper is ...
Roberts and Burrill,
Spring 1995, Gain score grading revisited, Educational Measurement: Issues
and Practices, V14, #1
At 04:31 PM 6/22/00 +0000, you wrote:
>Rich Ulrich wrote:
>> These are not quite equivalent options since the first one really
>> stinks -- If you are considering drawing conclusions about causation,
>> you need *random assignment* and the two Groups of performance are the
>> furthest thing from random.
>>
>> Let's see: the simple notion of regression-to-the-mean says that the
>> Best performers should fall back, the Worst performers should improve;
>> that's a weird main-effect, which should wreak havoc with interpreting
>> other effects.
>> Or: If the Pre is powerful enough to measure potential, then a
>> continued-growth model says that Best performers should improve more,
>> even given no treatments.
>
>This pattern was described in an obit about two-three years ago in the
>NY Times. A statistician's obit noted that he'd found a flaw in the
>Israeli air force's training program. Apparently, the Israeli air force
>was punishing the worst performers in a test because this usually
>produced a better performance in subsequent tests and was supposedly
>much more effective than positive reinforcement. They'd found that
>positive reinforcement of the best performers often resulted in a poorer
>performance on the next test. This now-deceased statistician pointed
>out the confounding effect of regression to the mean on this assessement
>of negative and positive reinforcement. The effectiveness of negative
>reinforcement (punishment) could be nothing more than a chance effect.
>
>I wish I had the citation for the study or the obit.
>
>Does anyone else in the group have a citation of this study?
>
>--
>Eugene D. Gallagher
>ECOS, UMASS/Boston
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.
>
>
>===========================================================================
>This list is open to everyone. Occasionally, less thoughtful
>people send inappropriate messages. Please DO NOT COMPLAIN TO
>THE POSTMASTER about these messages because the postmaster has no
>way of controlling them, and excessive complaints will result in
>termination of the list.
>
>For information about this list, including information about the
>problem of inappropriate messages and information about how to
>unsubscribe, please see the web page at
>http://jse.stat.ncsu.edu/
>===========================================================================
==============================================================
dennis roberts, penn state university
educational psychology, 8148632401
http://roberts.ed.psu.edu/users/droberts/droberts.htm
===========================================================================
This list is open to everyone. Occasionally, less thoughtful
people send inappropriate messages. Please DO NOT COMPLAIN TO
THE POSTMASTER about these messages because the postmaster has no
way of controlling them, and excessive complaints will result in
termination of the list.
For information about this list, including information about the
problem of inappropriate messages and information about how to
unsubscribe, please see the web page at
http://jse.stat.ncsu.edu/
===========================================================================
