In the absence of parental choice as the ultimate form of accountability, attempts to promote school achievement through standardized tests will always have limitations.

Derek A. Neal and Diane Schanzenbach, both of the University of Chicago, point out in a recent NBER working paper that how you choose the proficiency level makes all the difference.

Under NCLB (and previous reforms), they write, students at both ends of the bell curve get shortchanged:

"Accountability systems based on these metrics often provide incentives for teachers and principals to target children near current proficiency levels for extra attention, but these same systems provide weak incentives to devote extra attention to students who are clearly proficient already or who have little chance of becoming proficient in the near term."

Meanwhile, the Thomas B. Fordham Foundation says that some states are, well, cheating on proficiency tests. Who suffers? Children: "students may be performing worse in reading, and worse in elementary school, than is readily apparent by looking at passing rates on state tests."

Naturally, such findings don't play well in states that are labeled as slackers. Of the state of Michigan, for example, Fordham has this to say: "We found that Michigan's definitions for proficiency in reading and mathematics are less difficult than the standards set by most of the other 25 other states in this study."

A spokesman for the Michigan Department of Education told the Detroit News : "This report compares apples and oranges, adds unknown ingredients and yields lemonade."

So what's the solution? The authors favor national standards, saying "it's crazy" not to have them. "If the feds won't act," they write, "the states should, by coming together to agree to common, rational, workable standards ...."

That's not going to sit well with federalists (me included). On the other hand, one part of the proposal makes sense--decide what an 18-year old should know, establish standards for that point in time, and then work towards the earlier grades.

An even better path would eschew expert-driven, top-down approaches and move towards a competitive marketplace in education. Generally, millions of consumers (in this case, parents) do a better job of setting standards than a small panel from on high.