Posts Tagged ‘Interesting Uses of Data’

P.S. 8 in Brooklyn Heights gets an F. Really?!

Friday, September 19th, 2008

Is this a case of “question the data when it tells you something you don’t want to hear”?

Or is there something genuinely broken about NYC’s grading system? How could a school in a neighborhood where the median home sale price for June-August of this year was $2.775 million receive a failing grade? For that matter, what is an F going to do to the median home sales price? (But that’s neither here nor there.)

For what it’s worth, I think the grading system sounds reasonably well thought out: 5% is based on attendance, 10% on parent surveys (which actually gives P.S. 8’s parents an opportunity to influence the grade by expressing their satisfaction over the schools various extra-curricular activities.)

The lion’s share of the grade is based on year-over-year improvement (not for a particular grade, as in this year’s 4th grader’s versus last year’s 4th graders, but for the same class of students: this year’s 4th graders versus last year’s 3rd graders.) It’s a subtle, but importance difference.

In effect, what’s being measured is year-over-year improvement of the students, not the teachers. The remaining 25% is based on median scores (but calculated against other schools and schools with similar demographics).

Still, F seems a bit harsh. And the consequences of receiving an F sound harsh too.

Mr. Klein has said that schools that receive a D or an F two years in a row could be closed or the principal could be removed.

So, is NYC really better off without P.S. 8 than with it?

Perhaps there is something not quite right about the algorithm. Unless I’m completely misunderstanding this third-hand account of how the algorithm works, recent demographic changes in the P.S. 8 district that may be the reason why the school received an F, as opposed to a D or C. (P.S. 8 received a C in 2007.)

A quarter of the students now qualify for free lunch, compared with 98 percent in 2002, and more than half the students are white or Asian-American, up from 11 percent in 2002. Most of these changes are happening among the youngest children, before tests begin in the third grade.

In short, P.S. 8 is now competing against some of the most privileged NYC schools. However, P.S. 8’s privileged (aka white) kids are for the most part, still too young to be tested. As a result, the burden of competing with the city’s other well-off schools is carried mostly by P.S. 8’s less privileged middle-schoolers.

However, this rather significant oversight in the city’s algorithm is not what P.S. 8’s parents (at least the ones who were quoted in the NYT article) are putting forth as evidence of the grading system’s inadequacy.

Several P.S. 8 parents suggested that the F said more about the grading system than the school. They cited events like the annual read-a-thon fund-raiser, an art program that culminated in student work’s being showcased at the Guggenheim, and the school’s recent selection as Brooklyn’s Rising Star Public Elementary School for 2008 by Manhattan Media, a publisher of weekly newspapers.

But, what does the Guggenheim have to do with anything? Not much, if you buy into the city’s reasoning for what the grading system is trying to measure.

What we want with progress reports is to measure what schools add to kids, not what kids bring to the schools, Mr. Liebman said.

So what’s the issue here? A fundamental disagreement about what should be graded? Dissatisfaction with how its graded? Sour grapes over the results of the grades?

It’s hard to imagine that anyone would have made a peep about the city’s algorithm if P.S. 8 had received an A. At the end of the day, we all lend too much credence to data that tells us what we want to hear and too readily discount data that surprises us with bad news. It’s a modern-day variant of “shooting the messenger“. Although in the case of P.S. 8, it seems like the messenger did kinda munge up the message a bit, it certainly wasn’t as badly as some would like to believe.

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