Over the past decade, national initiatives have shifted States' attention to the challenge of turning around low-performing schools. The lack of consistent, dramatic improvements in the lowest-performing schools reflects the severity of the school turnaround challenge, but also suggests the need to continuously evaluate and refine turnaround…

North Carolina says it graduates 97 percent of its high school students, while Washington state reports it gives diplomas to just 66 percent. But researchers, using methods they believe are more accurate, estimate that the two states' graduation rates are essentially the same, at around 64 percent. Acknowledging that such disparities in data are…