Douglas Harris (respected author of Value-Added Measures in Education) in the Answer Sheet post above cautions against simple use of these measures in evaluation models and some quotes of his are worth repeating here.
“..they [states and administrators] also made one decision that I think was a
mistake. They encouraged—or required, depending on your vantage
point—states to lump value-added or other growth model estimates together with
other measures.”
“Teachers by and large do not like or trust value-added
measures. There are some good reasons for this: The measures are not very
reliable and therefore bounce around from year to year in ways that have
nothing to do with actual performance.”
“They [value added models] are statistically noisy, for example, and so many
low-performers ["ineffective teachers"] will get high scores by chance. [and conversely many effective teachers will get low scores by chance].”
I have been making these same points here for some time, so thank you Gotham News.
Harris goes on to describe how the models should be used as a screener rather than a simple teacher evaluation tool or measure itself. This is all well and good (and a bit complicated worthy of any academic) but his basic point that states and administrators have not understood the flaws in the value-added models in the first place, suggests that the sophisticated refinements that Harris suggests are not going to be treated any more fairly or understood any better by states and administrators than their first mistake.
I think Harris misses the point for the reasons that the value-added models are being mistakenly used is that the context is fundamentally politically driven by ulterior objectives and motives under the safe cover of “objective data”, which Harris points out indeed are flawed.
I don’t expect Harris’ observations will have much weight at the DOE of course, in the upcoming evaluation plan with the UFT, since the DOE still refuses to admit the points Harris has already made. The whole national context of this debate on “ineffective” teachers is appearing as some sort of national mass hysteria or witch hunt out of all proportion to any expected educational benefit by getting rid of the 2-3% that may indeed be ineffective.
Unfortunately, such is Blue-Red politics today in the USA in education, the upcoming “fiscal cliff” and other issues. It’s all very sorry to see.
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