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 common, state and federal officials are taking steps to make sure that states publish figures that compare graduation rates using the same scorecard. In the past two weeks, 46 governors signed a pact to produce graduation-rate data that more accurately gauge how well their states do at ensuring students finish on time. Separately, federal officials announced that the U.S. Department of Education would publish its own state-by-state graduation data along with the methodologically disparate rates states now report under the No Child Left Behind Act. The developments together constitute a big step toward producing data that tell policymakers whether their states are providing a sound high school education and that will help track efforts to improve high schools, backers of the changes say. The planned changes in reporting graduation rates are part of new efforts to improve the quality of high schools.