These are kids who want to get experience taking the PSAT a year early. These are also kids who would probably do well on the AP exams.
Yes, but while you can self-select for "takes the PSAT early," you can't really self-select for "gets a high score on the PSAT." And the conclusion we're drawing isn't, "people who take the PSAT in 10th score as well on the 11th grade AP test as people who take the PSAT in 11th do on the 12th grade AP test." It's "people who score well on the PSAT will likely score well on an AP test, regardless of whether they take those tests in 10/11 or 11/12."
