The debate over the “grade-point bump” is back.

Only months after officials decided to award a 10% grade bonus in Advanced Placement courses to all students at New York City’s public high schools, a study by an influential California researcher has found that gradepoint bumps for AP enrollment are unjustified.

Previous research by Saul Geiser was instrumental in convincing officials of the University of California system to downgrade the weight of the SAT in admissions decisions, which led the College Board to revamp the SAT for the first time in a decade. This time, Mr. Geiser set out to discover whether college freshmen who completed AP classes in high school turned out to be more successful than those who had completed only regular courses. He found that they didn’t.

“I don’t know whether they’re learn ing more because I have no direct way of looking at that,” Mr. Geiser said. “But I do know that they’re not performing any better in college than the kid who took the non-AP course.”

The research, which Mr. Geiser conducted with his colleague Veronica Santelices, is based on the records of 81,445 freshmen who entered the University of California system between 1998 and 2001.The report, which is currently under peer review, found that students who took AP exams and did well were successful college students. But just taking the advanced courses and not the exams – which was the case for the majority of the students – had “zero relationship” with college success.

Mr. Geiser was director of research for the University of California system until he retired last year, and he is now a researcher at the Center for Studies in Higher Education at the University of California at Berkeley. He said the bonus points awarded for AP grades at 70% of the schools across the country are unwarranted, because enrolling in AP classes does not predict better grades in college.

“The kids are getting the gradepoint bump simply for enrolling in these courses,” he said. “If they get a C, their grade points are counted as a B. If they get a B, their grade points are counted as an A. That doesn’t seem to be justified merely by the fact that they took the course.”

On January 8, about two weeks after the Geiser-Santelices study was completed, an independent pair of researchers affiliated with the Texas Schools Project at the University of Texas at Dallas reached the same conclusion.

The economics professors who wrote that report, Kristin Klopfenstein of Texas Christian University and M. Kathleen Thomas of Mississippi State University, wrote that college administrators and even state legislators are forming policy as if just taking AP courses has value. Legislators in California and Arkansas, for example, are requiring that all schools offer a minimum number of AP courses. Like Mr. Geiser and Ms. Santelices, however, the Texas researchers found that mere experience with AP courses does not contribute to college success.

Despite the new research, the New York City Department of Education is moving forward with plans launched this past fall to encourage more high school students to take AP courses and to give 10% bonuses to all students on their grades in AP courses.

Despite requests late last year, the department has declined to provide data about students’ performance on the AP exams. Nor would it say what percentage of New York City students who take AP courses take the end-of-course exams.

“We plan to weight AP courses higher not only because they have uniformity in content and assessments, but so that our students will be more likely to take the most rigorous course offerings,” a department spokeswoman, Michele McManus Higgins, said Friday. Referring to the Geiser research, she said: “As this report acknowledges, AP courses are a factor in gaining college admissions.”

From a college-admissions perspective, indeed, the findings of both sets of researchers suggest that giving extra weight to advanced courses puts children who didn’t have access to the classes at a disadvantage, even though there is no evidence they will be less successful college students. From a high-school administration perspective, the findings mean that granting bonuses might pointlessly reward children who on average learn no more than their peers in regular courses.

“I think that college admissions officers just have to be careful in terms of how they regard AP classes,” Ms. Thomas said.

She said the reasons that taking AP classes in high school isn’t making students more successful in college – though it does help them get in – are the rapid growth of the AP program and the inadequate attention paid to the quality and uniformity of AP courses that are offered.

The chairwoman of the City Council’s Committee on Education, Eva Moskowitz, said she hadn’t read the new studies and had never seen a written explanation of the new education department policy on AP grade bonuses. She said, however, that it doesn’t seem logical to give a bonus regardless of whether students work hard at the course.

“You give a bonus regardless of the quality of the work, just because kids show up?” Ms. Moskowitz asked. “The proof should be in the pudding – whether you do the work.”

She added that giving bonus points wouldn’t seem to be the best incentive system.

“To me, the way to incentivize is to have a school culture that rewards seriousness in general, and also to provide kids with a high-quality education,” she said. “If the courses are good, the students will come.”

Despite new questions, some New Yorkers outside the education department’s Tweed headquarters still favor the bonus points.

The author of books including “The Truth about Getting In” and “Rock Hard Apps,” Katherine Cohen, who is a former member of the Yale University admissions team, said unweighted grade-point averages mean that students who enroll in easy classes can be pushed to the top of the class rank, even when they are not challenging themselves. Weighting AP courses means that class rank doesn’t discriminate against students who push the envelope.

“I think it’s imperative for schools to weight AP classes,” Ms. Cohen said. “The level is that much harder. Advanced Placement is a college-level class.

“The no. 1 thing that colleges look at is rigorousness of course load,” she said. “That is before they even look at the grades.”