Rumberger and the other researchers will present their findings today during a conference at Cal State Los Angeles.
The Harvard report said that current education policies -- including those that require annual standardized testing of students -- may exacerbate the dropout crisis by creating "unintended incentives for school officials to push out low-achieving students."
The federal No Child Left Behind education law requires annual testing in most grade levels and also calls for schools to report their high school graduation rates annually.
Under the law, schools must raise their test scores and graduation rates or face possible sanctions.
In California, high schools can meet their graduation targets each year by showing any increase over the preceding year.
The Harvard researchers accused the state of failing to demand more from its high schools. State officials said they did not want to place demands on campuses based on data they believe are unreliable.
Any true gauge of graduation rates, they said, would depend on developing a system for tracking individual students as they move from school to school. Such a system has been in the planning stages for years but could begin tracking data next year.
"We know this is a serious issue, and that's why we have focused on high school reform," said state Supt. of Public Instruction Jack O'Connell, who has urged districts to increase graduation requirements.
Sponsors of the Harvard report urged the state to reexamine its approach to producing dropout and graduation data, and called for schools to redouble their efforts to retain students.
"Whether or not students graduate is the most important thing that happens to them in school," said Gary Orfield, director of the Harvard Civil Rights Project. "If students don't make it through high school, they really have no chance in our economy."
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A study found that less than three-quarters of California's high school students graduated with their class in 2002.
Source: Urban Institute
Graduation rates in California's five largest school districts
*--* Enroll- All Ment students Asians Latinos Blacks Los Angeles Unified 735,058 45.30% 76.70% 66.70% 39.10% 46.50% San Diego City Unif. 141,599 63.80% 81.20% 77.50% 49.20% 52.00% Long Beach Unified 96,488 69.10% 82.70% 78.70% 62.60% 59.40% Fresno Unified 81,058 59.00% 76.60% 66.10% 47.40% 46.30% Santa Ana Unified 61,909 72.50% 79.80% 65.80% 72.60% 70.50%
Source: Urban Institute
Times staff writer Erica Williams contributed to this report.