<p>I don’t know the precise formula, but the percentage of students taking the PSAT also factors in, indirectly. NMSC looks at the percentage of HS students in your state, and then determines the number of finalists as that same percentage of semifinalists (if 2% of HS seniors are in your state, then 2% of the finalists will be from your state). </p>
<p>If 100,000 students took the PSAT, and they were looking for 600 qualifiers, that would be 0.6% - a little more than half the students who scored in the 99th percentile. If a state with the same population had 30,000 students take the PSAT (because they focus on ACT over SAT), then those same 600 qualifiers would represent 2% of the test takers! It’s to your benefit to take the test in a state where most prefer the ACT over the SAT.</p>