Interesting excerpt relating to MAP that I found:
"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."
