Bluemagic, once again we have twin sons of different mothers. 99% ile! but Ds in class.
What does the Selection Index mean? It sounds like they use it later when actually selecting the scholars, but how is it used?
My understanding is the selection index is the score NM uses for selection. It keeps the score on a range similar to past PSAT scores. It is the subscores (Reading + Writing + Math)*2. This weights it heavier for kids who do better on the Reading/Writing side.
See..
http://blog.prepscholar.com/whats-a-good-psat-score-for-2015(Keep in mind this is a testprep center's page. And it's guesses for cutoff's are just guesses.)
