Shows that NWEA MAP test does in fact have a floor and ceiling. NWEA in its literature expresses that view that there is not an effective ceiling for the reason that only a small percentage of students succeed in getting scores outside the range that they deem to be valid. This logic is non-sensical.
Citation preview
Source of following:
http://www.nwea.org/support/article/532/rit-scale
Scale Variance by Subject Why do RIT scales vary from subject to
subject (e.g. the mathematics RIT scale goes higher than other
subject areas)? A ceiling effect exists when an assessment does not
have sufficient range to accurately measure students at the highest
performance levels. It has nothing to do with the actual numbers
attached to the scale and everything to do with the position of
students on it. For example, in reading, the RIT scale measures
with relative accuracy up to about 245.[*] This represents the 93rd
percentile at grade 10, and the 95th percentile at grade 8. If a
student scores above we know that student performed high but may
not be able to accurately assess how high they performed. Relative
to other tests, therefore, there is very little true ceiling effect
in this assessment. Even most high performing 10th graders receive
a technically accurate measure of their skill. [* The figure below
is from 2003 NWEA technical manual. The above passage indicates
that NWEA considers the valid range to end when SEM starts to
climne above 4 RIT points. By this criterion, the effective upper
limit to the valid range of the NWEA Math subtest is 270 RIT
points.]
