The Bush administration on April 1 announced that it will require states and school systems to report high school graduation rates in a uniform way, instead of using a variety of methods that critics say are often based on unreliable information.

Education Secretary Margaret Spellings announced the change at a news conference at which a report was released showing that 17 of the nation’s 50 largest cities had high school graduation rates lower than 50 percent.

Spellings said the high school dropout crisis is known as a “silent epidemic,” because the problem is frequently masked or minimized by inconsistent and opaque data reporting systems.

For example, she said, in some districts, a student who leaves school is counted as a dropout only if he or she registers as one. In others, a dropout’s promise to get a general education diploma at an unspecified future date is good enough to merit “graduate” status. These “loose definitions” of what it means to graduate contribute to the confusion over graduation and dropout rates, she said.

The department’s proposal to solve this problem involves the No Child Left Behind Act (NCLB), which currently allows states to use their own methods of calculating graduation rates and set their own goals for improving them.

Spellings and others have previously said a revised NCLB law should make states provide graduation data in a more uniform way. However, efforts to rewrite the law on Capitol Hill have stalled.

Under the 2002 law, schools that miss progress goals face increasing sanctions, including forced use of federal money for private tutoring, easing student transfers, and restructuring of school staff.

Using a common method to evaluate graduation rates for cities, the dropout report—from the America’s Promise Alliance—found the lowest graduation rates in Detroit, Indianapolis, and Cleveland.

It found that about half of the students served by public school systems in the nation’s largest cities receive diplomas; students in suburban and rural public high schools were more likely to graduate than their counterparts in urban public high schools.

Nationally, about 70 percent of U.S. students graduate on time with a regular diploma, and about 1.2 million students drop out annually.

“When more than 1 million students a year drop out of high school, it’s more than a problem, it’s a catastrophe,” said former Secretary of State Colin Powell, founding chair of the alliance.

The group announced plans to hold summits in every state during the next two years on ways to better prepare students for college and the work force.

The report found troubling data on the prospects of urban public high school students getting to college. In Detroit’s public schools, only 24.9 percent of the students graduated from high school, while 30.5 percent graduated in Indianapolis Public Schools, and 34.1 percent received diplomas in the Cleveland Municipal City School District.