In 2005, Nebraska and six other states had on-time high school graduation rates higher than 85 percent, according to government estimates.

Washington ? If Congress doesn’t get the job done, Education Secretary Margaret Spellings says she’ll consider using her authority to require states to report high school graduation rates in a more uniform and accurate way.

“I think we need some truth in advertising,” Spellings said in an interview, referring to the hodgepodge of ways states now report graduation data.

States calculate their graduation rates using all sorts of methods, many of which critics say are based on unreliable information about school dropouts.

Republicans and Democrats in Congress have drafted proposals to better gauge how well high schools are doing at getting students diplomas, and doing it on time. The changes are part of a rewrite of the No Child Left Behind education law, but that bill’s progress has stalled amid disputes over unrelated testing and teacher pay issues.

Spellings said if that standoff persists, her department has the power to address the reporting of graduation rates. “I think it can be done through regulations,” she said.

There is an overwhelming consensus among politicians, educators and academics that states must do a better job. Spellings pointed to a two-year-old agreement by the nation’s governors to adopt a common method of calculating high school graduation rates.

It calls for states to develop systems that track individual students throughout school and record whether they transfer, drop out or graduate. In general, students who graduate on time and with regular diplomas would count toward a state’s graduation rate. Research indicates students who take extra time to graduate or get alternatives to diplomas, such as a GED, generally don’t do as well in college or the work force.

Under No Child Left Behind, states may use their own methods of calculating graduation rates and set their own goals for improving them. Critics say that’s a loophole.

Some states, for example, give themselves passing grades as long as they make any progress at all on graduation rates from year to year.

States’ methods of counting graduates also are flawed and lead to overestimates, according to reports by both the Education Trust, which advocates for poor and minority children, and the Alliance for Excellent Education, another group focused on the issue.

For example, Florida – which does track individual students – includes those who receive GED certificates in lieu of diplomas when calculating its high school graduation rate.

And New Mexico counts the number of enrolled 12th graders who graduate as its rate. That is problematic because most dropouts leave school before their senior year.

The state has started to track individual students through the education system but doesn’t yet have enough data to report its graduation rate that way, New Mexico Secretary of Education Veronica Garcia said in a telephone interview.

North Carolina used to report the percentage of graduates who completed high school on time, completely ignoring those who dropped out early. That gave the state a 95 percent graduation rate. When the state recently switched to the tracking method backed by the governors, its rate plummeted to 68 percent.

North Carolina Republican Sen. Richard Burr, a member of the education committee, said other states should be pushed to take the same tough step. “Let us for once compare apples and apples,” he said.

The most common methods used by states to calculate graduation rates assume there’s good data on the number of dropouts, something that generally doesn’t exist. A student who stops coming to school, for example, often is assumed to have moved and gets counted as a transfer, when in fact the student may have quit school.

“If you use dropout data, you need to be very concerned,” said Chris Swanson, director of the Editorial Projects in Education Research Center, which has published studies on the issue.