Acknowledging that reported graduation rates have been less than accurate across many states, 45 of the nation’s governors, including John Baldacci, this week agreed to adopt similar, more thorough measures so that fair comparisons could be made. This was a good decision, but the governors should be clear about what they are measuring.

A recent report by The Education Trust showed what many education officials already knew: States do not report their graduation numbers accurately, in part because some of them do not start counting students until they are in 11- or 12th-grade, when most students who drop out have left by then. Maine, for instance, reports its graduation rate at 87 percent; The Education Trust puts it at 72 percent.

The trust, however, does not count students who earn general equivalency diplomas, which Philip Trostel, a professor of economics, and Olena Trymaylo, an economics student, at the University of Maine argued persuasively in these pages recently should be counted. Those who attain GEDs, they write, have similar employment rates and go on to earn wages similar to those with high-school diplomas. Some go on to earn college degrees, they write.

If the purpose of measuring graduation rates is to see how many students have been prepared for work or higher education, then counting GED students makes sense. If, on the other hand, the data are measuring a school’s success in graduating students through its standard route, then leaving out GED students and, for instance, those who require five or six years of high school is understandable.

The governors answer the question in their nonbinding agreement by creating complementary graduation rates. One counts only the number of graduates compared with the number of ninth graders four years earlier, factoring in transfers. A second rate would be much more expansive, counting GED attainers and others.

Professor Trostel would add a more telling measure to the dropout measure: Years of schooling completed. Now, drop-out rates do not distinguish between the student who quit after eighth grade and the one who was a single course short of receiving a diploma. The difference, certainly, affects the view of both how fit a student is for further education and how well a school system reached the student.

Measuring anything is dull if there is not a good reason behind the exercise. The governors report the higher standards were the first step to a reassessment of high school courses to make them more rigorous. Politicians have been talking unsuccessfully about making schools harder at least since Sputnik. Perhaps a reason for this is their lack of understanding about how many students they were losing along the way or who were choosing alternate routes to diplomas. If so, the agreement should help.

It is remarkable given the decades of organized public schools and the countless billions of dollars spent on them that some important information such as graduation and drop-out rates remains only loosely known. Governors should have acted on this years ago. Now that they have, the faster and more uniformly they can move, the better.