MAP testing is computer-adaptive, meaning that the questions become easier or harder depending on how a student responds. Our schools use it to periodically measure student growth.
Our schools also use it, along with other teacher-assessments, for appropriate group placement (groups are flexible). It is used, along with other criteria, as a part of the screening criteria for our G&T program.
The Rausch UnIT/RIT scale it also uses is supposed to be continuous, so a 3rd grader with a given RIT score, can check to see what percentile his score would place him in as compared with 2nd, 4th and 5th graders.