In years past (and I assume this year, too), the Selection Index percentile was a national percentile. In guessing whether a kid will be NMSF, you need to consider that NMSF are the top 1% in your state. If you are in NJ, 99th percentile in the state is 99th+ nationally. If you are in WV, 99th percentile in your state is about 97th percentile nationally. That SI is the only thing used in "selecting" NMSF.
No one really knows what the cutoffs will be this year. But historically high scoring states will still be high scoring states, historically low ones will continue to be low scoring.
After one is named a NMSF, you need to fill out some info online and write an essay. Your HS will fill out some info about you and transmit your transcript to NMSC. You need to take the SAT (anytime October sophomore year to December senior year) and submit to NMSC. The SAT score does not need to match your PSAT score. Under the "old" SAT, a score of 1960 was needed to advance from NMSF to NMF.
About 15,000 of the 16,000 NMSF advance to NMF. Maybe the most common reason those 1,000 do not advance is due to some Cs (or Ds, Fs) on the transcript. There are years when kids still made it with several Cs, and there are years when more than one C stopped kids from advancing to NMF.
