Twenty two states have better high school graduation rates than Ohio under a new, more uniform method of calculation, according to data from the U.S. Department of Education.

The department required states to adopt the more rigorous, uniform four-year graduation rate that officials say doesn’t undercount dropouts and produce inflated results. The data is from 2011, the first year for which all states used the common measure. The formula redefines “on-time” as any student who graduates within four years of their high school start year.

Ohio’s new graduation rate for all students is 80 percent, which ties for eighth with Hawaii and Wyoming, according to the data released on Monday.

Iowa had the best graduation rate at 88 percent, while Nevada ranked 47th at 62 percent. Multiple states tied for second through eighth place. Kentucky, Idaho and Oklahoma have not yet reported their data.

Michael Sawyers, Ohio’s acting superintendent of public instruction, said Tuesday there are “significant opportunities for improvement” in the graduation rates for some subgroups, specifically for students who are African American (59 percent) and Limited English proficient (53 percent).”

“That is not acceptable,” he said. Ohio’s data also showed an 85 percent graduation rate for white students and 65 percent for those who are economically disadvantaged.

By comparison, Ohio’s graduation rate for all students was 84.3 percent in 2010 under the old methodology.

The U.S. Department of Education said the varying methods formerly used by states to report graduation rates made comparisons between states unreliable, while the new, common metric can be used by states, districts and schools to promote greater accountability and to develop strategies that will reduce dropout rates and increase graduation rates in schools nationwide.

“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 in a news release. “Ultimately, these data will help states target support to ensure more students graduate on time, college and career ready.”

While 26 states reported lower graduation rates and 24 states reported unchanged or increased rates under the new metric, the changes should not be viewed as measures of progress but rather as a more accurate snapshot, the U.S. education department noted.