The National Research Council’s long-awaited assessment and rankings of doctoral programs has been postponed again.

The influential report is now slated for release late next spring, said Charlotte V. Kuh, the council’s deputy executive director of policy and global affairs and director of the project, in an interview this morning. “We are giving ourselves a little breathing time,” she said.

Members of the committee overseeing the project reviewed the assessment statistics this week, and, in aggregating the data, they found anomalies that they felt needed double-checking, she said.

“We are committed to publishing data that is as valid as we can possibly make it,” Ms. Kuh said. “When you see anomalous data, you have three choices. You can publish it as is, you can just say ‘n/a,’ or you can give the schools a chance to make sure they’ve got it right.” Her staff will be talking to colleges whose figures appear incorrect.

The committee also wants extra time to educate colleges about the study’s methodology, which is quite different from that of the council’s previous study, published in 1995, said Ms. Kuh.

Just last month the council was planning to release the rankings in February. While she would not commit to a specific date, Ms. Kuh said she expected the report to be out between mid-May and mid-June. —Jean Evangelauf