USA Today and "too good to believe" test scores

USA Today published a big article over the weekend after looking at test scores in Ohio, Michigan, Arizona, California, Florida, and Washington, D.C. on "Test Scores Too Good To Believe."

Thomas Haladyna, a professor emeritus at Arizona State University, says test gains of 3 standard deviations or more for an entire grade are "so incredible that you have to ask yourself, 'How can this be real?' " Haladyna says such a spike in scores would be like finding "a weight-loss clinic where you lose 100 pounds a day."
In the past decade, similar score spikes uncovered by The Dallas Morning News and the Atlanta Journal-Constitution, using the same methods as USA TODAY, led state officials in Texas and Georgia to conduct major probes of hundreds of schools.

A useful read for those wondering just how they figure such things out.