You can identify an elite high school from public data. It takes two numbers rather than one, and the second is the one nobody publishes.
The first is the UC Reach Score: admits to Berkeley, UCLA, San Diego, Santa Barbara, Irvine and Davis, per 100 seniors. A high score means the class collected a great many UC offers.
The second is yield — how many of those offers turned into enrolments. Low yield means most of them were turned down. Across California it runs 69%, high mostly for an unremarkable reason: a student admitted to four campuses can only enrol at one, so three offers get declined by a kid who is happy with the fourth.
Each says something on its own. Together they say a great deal more, and they identify something specific.
Nineteen California schools posted a Reach Score of 80 or better on at least 100 admits last year. Seven show a turn-down rate above 82%.
Sage Hill School, Newport Coast — Reach 151, 223 admits, 91% turned down
The Webb Schools, Claremont — Reach 144, 86%
The Harker School, San Jose — Reach 126, 88%
Flintridge Prep, La Cañada — Reach 103, 83%
Stevenson School, Pebble Beach — Reach 95, 87%
Crean Lutheran High School, Irvine — Reach 94, 84%
Notre Dame High School, San Jose — Reach 94, 83%
The obvious objection is that these students simply took a less selective UC instead. They did not — the turn-down rate across all nine UC campuses is identical to the top-six figure for every school listed. Those classes left the system. At this level of outcome that means the Ivies and the schools that compete with them.
Two limits worth stating. Every figure is a floor, because UC suppresses any per-campus enrolment count below three students, so the real share is that or higher. And we hold no enrolment data outside the UC system, so the destination is a very strong inference rather than something we measured.
And the schools on the other side of this — Whitney, Canyon Crest, Lynbrook, Monta Vista — are not producing a lesser result. A class that fills Berkeley and UCLA is doing exactly what most California families are hoping for, at a fraction of the cost.