Nora:
 
Could someone explain to me the reasoning behind this method? 
 
It's all about what the state regulations indicate. It is clearly not
logical. The IQ-discrepancy model has been widely demonstrated to be an
unreliable method for identifying students who have reading
disabilities. The discrepancy model has lots of problems, one of which
is that it tends to over identify higher IQ students, and under identify
lower IQ students. Articles about the problems were published in 1998,
but many states continue to at least include the discrepancy model in
their regulations. After I read the attached article, I was astonished
that at the time (2005) most states still required the use of the
discrepancy method. We have to follow the laws, even if they are deeply
flawed. NM recently switched to an RtI model.
 
This regression
effect leads to observed discrepancies
that are larger, on average, than
the true discrepancy for individuals
with IQ scores above 100 and, therefore,
increases the chances that such
children will be identified as IQ discrepant.
For individuals scoring below
the mean on IQ, the opposite tendency
occurs, making the observed discrepancy
smaller than the true discrepancy,
on average, so that their chances for
identification as IQ discrepant are
reduced.
 
Brant Hayenga
Educational Diagnostician 
Stapleton Elementary/Rio Rancho Middle School
(505) 896-0667 ext. 226 (District Office)
(505) 891-8473 ext. 519 (Stapleton Elementary)
bhayenga at rrps.net
 
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