Prep Schools and
Test Scores
How
do we rate teachers and schools? One
way, which has the advantage of being objective, but which is still
controversial, is to consider their students’ test scores, and how much they go
up while the students are being taught by a given teacher or at a given
school. The No Child Left Behind Act has
likewise mandated tests for most public school students at a few points in
their schooling. We don’t have such
mandated tests at private schools, but many private high schools (“prep
schools”) require Secondary School Admission Tests (SSATs) of all their
applicants, and have graduates who almost uniformly are applying to colleges
and taking the SAT test.
This
scatter graph shows information on the students’ testing at several prep
schools which might be of interest to a student living in Massachusetts or New
Hampshire, and which have released testing information to Boarding School
Review (n.d.).
For
each school, the horizontal location of the bubble marking the school shows how
well the school’s students tested when they applied to the school (the average
SSAT score, measured as a percentile, of incoming students). And the vertical location of the bubble shows
how well the school’s students test in their senior year at the school (the
average SAT score, on a scale which goes to 2400) of graduates.
Since
the SSAT and SAT test essentially the same thing (preparation for academic
schoolwork, a combination of intelligence and learning measured mostly with
regard to mathematical understanding, vocabulary and reading skill), we should
not be surprised to see a fairly strong correlation between the two statistics. This correlation can be expressed by an r2
of 78%, or by noting how nearly the schools’ bubbles fall along the best-fit
diagonal trend line, as shown:
To
the extent each school deviates above the trend line, we can say that the
school is doing an above-average job of educating its students (at least, to
the extent that SAT scores reflect education), and schools below the trend line
appear to not be doing so well on this measure.
(The size of each circle indicates the number of students at the school;
the color green indicates a girls-only school, blue a coed school, orange a day school.)
However,
the information in this graphic should be a rather small part of judging a
school’s academics, and academic strength may not be the most important factor
when judging how happy or successful a particular child will be at a particular
school.
Further,
the height of the dots above the diagonal line may not be as important in
choosing a school as is where the school falls along the diagonal line. Although most people want to go to the most selective
prep school (or college) that they get into, it is unclear whether this is the
ideal choice in terms of academic progress, let alone social life. Imagine a student who scores at the 90th
percentile on the SSAT. At a school near the center or on
the left of the chart she will be among the stronger students; this may lead to
increased self-confidence and self-identification as a scholar; on the other
hand, it may instead lead to laziness as a moderate effort may be all that is
necessary to have average or even above-average grades. At an academically tougher school on the
right of the chart, the 90th-percentile scorer will likely not be
among the stronger students; this may lead to harder work to keep up with
peers, or it may lead to frustration and burnout. So in choosing a school, one might have to
guess whether one’s child is more likely to suffer from laziness or from low
self-esteem.
A
final caveat: With any system of measurement, the accuracy of the measurement
goes down to the extent that the measured entity or the measurer has a stake in
the outcome. And as with public schools,
colleges and law schools, prep schools have in the past sometimes fudged input
and outcomes statistics. One wouldn’t
want to penalize a school for being honest.
References
Boarding School
Review. (n.d.). Retrieved from http://www.boardingschoolreview.com/
SSAT.org.
(2013). Scores: How to read your score report. Retrieved from www.ssat.org/scores/read-score-report
