Parents ask me this more than almost anything else, usually in eighth grade and usually with a tuition bill or a house purchase attached. I went looking for numbers.
What the data shows about high school admissions impact
The most detailed public attempt to measure this is the Elite College Placement Index from Chicardgo School. It estimates what share of each high school’s graduates enroll at a top 25 national university. Across 30 metro areas the gaps are large, and they are not consistent.
- Chicago: the median private school sends 12% of graduates to a top 25 university. The median public school sends 3%.
- Washington, DC: 25% private, 3% public. The widest gap in the dataset.
- Bay Area: 15% private, 8% public.
- Phoenix and Atlanta: 4% private, 4% public. No gap.
- Milwaukee: 1% private, 5% public. The gap runs the other way.
Inside the public system the spread is just as wide. In Nashville the median magnet school places 8%, against 1% for public schools overall. In Chicago, the index puts Payton at 24%, IMSA at 23% and Northside at 20%, level with the strongest private schools in the city.
One caution before you act on any of it. Chicardgo states that its matriculation figures are modeled estimates built from school profiles and state data, not official counts from the schools. I use them for direction, not decimals. For real numbers on a specific school, ask its counseling office for the school profile and the matriculation list.
The gap is mostly who walks in the door
A school that sends 24% of its class to top 25 universities admitted that class by test score. The question that matters for your student is different. Would the same student do better there than at the alternative?
Economists have tested this directly by comparing students who scored just above an exam school’s admission cutoff with students who scored just below it. These are near-identical students who ended up in different buildings.
In Boston and New York, researchers at MIT and Duke found that attending an exam school, Stuyvesant and Bronx Science included, had little effect on test scores or on the quality of college students later attended. They titled the paper The Elite Illusion.
Chicago has its own version. Researchers from the Federal Reserve Bank of Chicago and the UChicago Consortium on School Research studied students entering CPS selective enrollment high schools from 2010 to 2013. They found no effect on test scores. Students did report better experiences, including stronger relationships and feeling safer. But for students from the lowest-income neighborhoods, admission lowered grades and lowered the probability of attending a selective college. The authors point to class rank as the likely cause. The same student ranks lower in a stronger room.
Where the school does change the outcome
It is not nothing. Raj Chetty, David Deming and John Friedman linked admissions records from several Ivy-Plus colleges to test scores and tax data. Among applicants with comparable SAT or ACT scores, students from private high schools received much higher non-academic ratings and no higher academic ratings.
The private school edge at the most selective colleges does not show up in the academic rating. It shows up in everything else: activities, recommendations, how the student comes across on paper. My reading is that this reflects counselors with small caseloads, teachers who write detailed letters, and families with the resources to support real pursuits. The same study found no such advantage at flagship public universities.
What I tell families
Stats are the floor, not the ceiling, and the research says the same thing about high schools. The building does not move the floor much. What separates applicants sits above it, and that part belongs to the student.
So I would not pay tuition or move houses for a feeder rate. Colleges read every applicant against what their own school offers, which is why the school profile travels with every transcript. A student near the top of a solid school, taking the hardest courses available and doing real work outside class, is not at a disadvantage against a student in the middle of a famous one. Often it is the reverse.
Pick the school where your student will be challenged, known by teachers, and have room to build something. Then ask what the student is going to do with four years there.
