The Department of Education releases a new set of figures -- and the gaps are wide.

Mike Segar/Reuters

For the first time since the nation's governors agreed to use the same formula to calculate high school graduation rates, the U.S. Department of Education has published state-by-state figures that allow apples-to-apples comparisons of student achievement.

The data are for the 2010-11 academic year and show Iowa with the nation's highest graduation rate of 88 percent. Nevada finished last among the states at 62 percent. (The U.S. average graduation rate has not yet been released because several states still have to be reported.)

As Education Week's Politics K-12 blog points out, the new report shows considerably wide achievement gaps among minority and economically disadvantaged students when compared with their more affluent white peers. In Michigan, for example, the graduation rate for black students was 57 percent, compared with 80 percent for white students.

The new formula for calculating graduation rates is straightforward: States report the percentage of first-time ninth graders who earn a diploma within four years. Students who receive adjusted diplomas (typically an option for students with disabilities) or GEDs are not counted. The new graduation rate formula is the result of a nationwide initiative that dates back to 2005, when the governors of all 50 states signed a compact agreeing to adopt the new formula by this year. (The District of Columbia also agreed to participate.)

With the release of the 2010-11 data, the baseline for each state's graduation rate has been reset. It's important to remember that the newly reported graduation rates are not directly comparable to those previously calculated by states using alternate metrics. Under the new formula, slightly more than half of the states saw their graduation rates decline, while the remaining states either saw an increase or stayed the same, according to the U.S. Department of Education.

So why does this matter? The formulas previously used by some states were considered highly inaccurate: Dropouts were often widely under-reported, while graduation rates were inflated. The new formula is a move toward more accountability, as well as consistency. Additionally, the wide disparity in states' formulas for calculating graduation rates made it difficult for researchers and policymakers to compare outcomes. That's a necessary element for identifying and addressing the underlying issues contributing to nearly 30 percent of the nation's ninth graders failing to earn a diploma in four years.

"By using this new measure, states will be more honest in holding schools accountable and ensuring that students succeed," U.S. Secretary of Education Arne Duncan said Monday. "Ultimately, these data will help states target support to ensure more students graduate on time, college and career ready."

That's the hope of Jim Guthrie, Nevada's recently appointed superintendent of public instruction.

"You can't solve your problems if you don't know what they are," Guthrie told the Las Vegas Sun. "We need accurate information, and more of it."

This post also appears at The Educated Reporter, an Atlantic partner site.

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