Someone mentioned the percentiles for the SI’s are based on last year’s data – I am not seeing that specified in the 2015 report although in the 2014 report it is clearly stated:
In 2014 it says "Selection Index Percentiles and Mean Score
can be used to compare a student’s performance with that of juniors.
Points to note
Reported on a scale ranging from 60 to 240, the
Selection Index is the sum of the critical reading,
mathematics, and writing skills scores. For example,
a critical reading score of 56, a mathematics score of
62, and a writing skills score of 59 would result in
a Selection Index of 177 (56 + 62 + 59).
Percentiles are based on the Selection Index
earned by college-bound juniors who took the
PSAT/NMSQT in the previous year.
But I do not see anything similar in the 2015 report about the origin of the percentiles indicated in the chart for SI’s - so I wonder if it is at least based upon a “sample” of actual test takers if not a majority of them. If so, the info should be pretty reliable to estimate many if not all of the state cutoff scores assuming the make-up of the pool of test takers is not hugely skewed this year bc it was only given on a school day. (Our school offered it to all but less than 50% of juniors took it.) I agree that learning the official SI for “Commended” status will provide an official baseline.