Arne Duncan’s useful exaggeration

This from Jay Mathews at WaPo's Class Struggle:

As my colleague Nick Anderson reported recently, Education Secretary Arne Duncan estimates that 82 percent of U.S. public schools will miss their academic targets this year as the federal No Child Left Behind law raises the bar higher than most schools can jump.

This was predicted by many experts when the law took effect in 2002. Its demand that nearly all students be proficient in math and reading by 2014 was hopeless, but unavoidable. Members of Congress knew they would be ridiculed if they passed a law saying that 15 percent, 30 percent, 50 percent---pick your favorite number—of children would not learn.

What is most interesting about Duncan’s estimate, however, is not that so many schools are unable to meet the law’s standards, but that so many experts insisted Duncan’s expected 82 percent failure rate for 2011 was wildly exaggerated. Only 37 percent of schools missed their targets last year. This year’s percentage will be more than that, experts said, but nowhere near that much.

What is going on is an old clash of statistics and politics.