I lost which thread I was on… anyways
There are two different routes - Convergence Table and User Percentiles - to take on.
The two routes conflict with each other, so do not mix these two for any prediction/analysis.
Following the User Percentiles data route,
we established 1390 is the lowest USER 99%ile score.
Possible S.I. ranges for 1390 are 202 - 215 corresponding to very mathy (low-english) kid [760 math + 630 R+W] to [630 math + 760 R+W] perfect english kid.
Thus, the ** USER 99 percentile Selection Index must lie between 202 - 215. **
All the kids with 216 S.I. have 1400 or above PSAT scores (above 99%,) and all with 201 S.I. have 1380 or below (below 99%.)
Now, we line up the 1390 kids with their S.I. scores and have 98% or below kids stand-by.
Since S.I. has double weighting on R+W, for any potential 90%ile S.I. below 215, some very mathy kids get kicked out of 99% S.I. club to 98% or below, and perfect english kids with 1380 or below join the 99% club.
If 99%ile S.I. line goes down too low, e.g. 202, then the whole population of 1320 kids get to join 99% S.I. club and it swells to 97% PSAT score club so that’s too much. Going through this exercise, one can estimate
USER 99 percentile S.I. line must lie between ** 205 - 209. **
It needs to include all the kids with 99% R+W score (700) but cannot include majority of 1340 kids.
Soon someone will bring us new data. The 99 Percentile Selection Index from GC.
If that value lies outside of the above range, we will have three conflicting routes:
Convergence Table; PSAT score and subsection User Percentiles; S.I. Percentiles from GC
What A Joy!