

Method to Grade Teachers Provokes Battles - px
http://www.nytimes.com/2010/09/01/education/01teacher.html?_r=1&hp

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yummyfajitas
A common criticism of measuring teacher performance is that teachers will try
to get the best students in order to get the highest bonuses. Apparently VAM
solves this problem:

“My kids come in at a very high level of competence,” [...] After she teaches
them for a year, most score highly on a state science test but show little
gains, so her bonus is often small compared with those of other teachers..."

It seem as if VAM gives teachers an incentive to seek out the students that
they can help the most. Win.

~~~
locopati
It still assumes that the teacher has the most influence over their students,
rather than the parents & the environment. I do not know if studies show
results one way or the other here (suspect it's rather hard to tease apart).

A possible analogy would be that my bonus depends on the work of my teammates
(and by extension, their environments). Except, in that case, my teammates
have control over their environments are possibly more skillful than a student
at managing their situations.

Mind you, I'm not saying that teachers shouldn't be evaluated. Just don't
think this will be a magic bullet. And numbers have a way of taking on a life
of their own, as if by quantifying something we are establishing something
meaningful. In reality, the numbers will be used to justify whatever political
agenda is running the show.

That, quite reasonably, is what the teachers are concerned about.

~~~
yummyfajitas
_It still assumes that the teacher has the most influence over their students,
rather than the parents & the environment._

No it doesn't, since VAM measures deltas. Why would a poor environment cause a
group of students to do well in the 3'rd grade, but poorly in the 4'th grade?
If environment is the determining factor, then the value added should be close
to zero for most teachers.

Some individual students may have their environment change, but this will
average out over many students (with high probability).

~~~
MichaelSalib
Imagine two groups of students in two different environments. If students in
the bad environment are incapable of realizing significant gains regardless of
their teachers whereas students in the good environment are likely to manifest
gains no matter how bad their teachers are, then comparing deltas won't help.
What you'd need to do is rotate teachers into a variety of different
environments. I mean, even a mediocre teacher should produce significant gains
for a class of wealthy students: the more mediocre the teacher is, the more
private tutoring her students will get to compensate.

Consider graduates from selective engineering schools like MIT. They tend to
be very good. Does that mean that MIT is really good at undergraduate
education? Of course not. In fact, MIT is pretty bad at undergraduate
education. But that doesn't matter because the world's best engineering
students are desperate to attend MIT and MIT can pick and choose.

I think this method holds promise, but like the GP, it is hardly a silver
bullet.

~~~
yummyfajitas
_If students in the bad environment are incapable of realizing significant
gains regardless of their teachers whereas students in the good environment
are likely to manifest gains no matter how bad their teachers are, then
comparing deltas won't help._

In that case, good teachers will avoid such students, and bad teachers will
seek them out. This is actually quite a highly desirable result - we won't
waste a good teacher on hopeless students, and a bad teacher can't harm them
much.

As I said, VAM gives teachers an incentive to target the students that they
can help the most. Now that I think about it, it also gives bad teachers an
incentive to target students they can't harm.

The more I think about it, the more I like it.

~~~
MichaelSalib
_In that case, good teachers will avoid such students, and bad teachers will
seek them out. This is actually quite a highly desirable result - we won't
waste a good teacher on hopeless students, and a bad teacher can't harm them
much._

That might be the case in a world where there was perfect information, no
barriers to entry, and no significant asymmetries. In the real world though, a
brilliant young teacher may get her start working with children damaged by,
say, lead poisoning, and get no results. As a result, she'll be branded as
incompetent. Since she's been branded as a bad teacher, she won't be able to
get jobs in high performing schools with better students and will never get an
opportunity to demonstrate her brilliance. Or she might be so discouraged by
her failure that she leaves the profess altogether. You can imagine the
equivalent problem faced by teachers of well-off children.

~~~
yummyfajitas
Nonsense. The students are hopeless and she has no power to help or harm them.
Hence, her students perform exactly as well as they are expected to and her VA
score is 0 (average). That's the beauty of VAM.

If student sensitivity is measured as well, she will simply be branded as
"inadequate information to evaluate performance". If you are concerned that
she might be really unlucky and get a class full of people worse than their
statistical predictor, that's what confidence intervals are for.

As for barriers to entry and imperfect information, VAM also doesn't provide
green energy or solve P=NP. All it does is improve incentives and give
administrators a better measure of teacher performance.

