is that people know they’re being measured. It makes for a flawed sample, because people know, say, they’re taking the placebo instead of the pain-killer. Or whatever.

Anyone who has worked in a gov’t institution or a publicly-traded company, or just seen a few episodes of the Wire knows that stats and numbers are more important than “reality” and that these numbers are often quite removed from whatever it is that actually exists.

Especially if your future is dependent on those numbers. So, should we trust testing? Heck no!

“Measuring,” said President Bush, in a discussion of his No Child Left Behind law, “is the gateway to success.”

Not only has high-stakes testing largely failed to magically swing open the gates to successful learning, it is questionable in many cases whether the tests themselves are anything more than a shell game.

Daniel Koretz, a professor at Harvard’s Graduate School of Education, told me in a recent interview that it’s important to ask “whether you can trust improvements in test scores when you are holding people accountable for the tests.”

The short answer, he said, is no.