ATLANTA — Nearly twice as many students dropped out of Georgia schools than were earlier reported, according to an analysis by The Atlanta Journal-Constitution.

The dramatic change in numbers happened because the federal government is forcing states to apply stricter standards when measuring the graduation rate. But the newspaper (http://bit.ly/OByD6y ) also found that the discrepancy stemmed from a failure to accurately measure how many students were quitting.

Documents obtained under the state's open records law showed that 30,751 students left high school without a diploma in the class of 2011. That is nearly double the 15,590 dropouts that were earlier reported. Under a new formula, the state's graduation rate dropped from nearly 81 percent to about 67 percent, one of the country's lowest.

There are several reasons for the change. This year, the federal government is making states use stricter standards when calculating graduation rates. For example, the new formula only counts graduates who earn their diplomas in four years. As a result, students who earn a degree in a longer period are not counted in the graduate rate.

It also appears that schools generally assumed that students who left had simply transferred to another school, even if there was no evidence to support that. In general, students were only counted as dropouts if they formally declared they were quitting. The new formula forces officials to count students who leave as dropouts unless there is evidence they enrolled elsewhere.

Education experts have long suspected that Georgia's graduation rates were too high. School districts had faced pressure under the federal No Child Left Behind law. To comply, Georgia committed to increasing graduation rates by 5 percentage points annually until reaching a perfect graduation rate by 2014.

The statewide graduation rate reached 80 percent in 2010, but it has fallen since.

"They spent more time trying to fix the numbers, than they did trying to fix the problem," said Cathy Henson, an advocate for education reform and former state Board of Education chair. "My frustration is that, if you're giving people phony data, then they don't understand the magnitude, the urgency of the problem."

Former State School Superintendent Kathy Cox said some districts may have undercounted dropouts.

"Some of this is catching people who were probably deliberately messing with the system, and some of this is catching what probably is just bad record-keeping," Cox said, speaking about the statistics.

Current schools chief John Barge denied the figures showed system-wide manipulation.

"I can't say that a system was or wasn't fudging the numbers," he said. "Do I think there is large-scale people wanting to manipulate the system? I really don't think so."