Mayor Rahm Emanuel says he told Chicago school officials to go back and fix the errors in the graduation rate that were first reported in June by WBEZ and the Better Government Association.

“Soon as there were questions raised, I said, ‘Go back, and analyze what’s going on and be accurate,’” Emanuel said. “And that’s exactly what they did.”

Chicago Public Schools officials announced late Thursday it would revise the past four years of graduation rates and make sure to include students who dropped out but were misclassified as having transferred.

“There was an error pointed out,” said CPS CEO Forrest Claypool. “We studied that information. We had to wait until the end of the summer schools to have all the data. And then we corrected it.”

Claypool said the errors “shouldn’t deflect from the fact that the trendline is up.”

The trendline is up — officials also announced late Thursday that the new 2015 graduation rate is 69.9 percent.

But the errors raise questions about how well the district is accounting for students who are still dropping out. Under Emanuel, CPS nearly doubled the number of alternative schools in the city and opened re-engagement centers to do the work of tracking down kids who are listed as dropouts. But the students who were misclassified wouldn’t have been officially listed as dropouts and no one would have known to track them down.

Emanuel agreed that’s cause for concern.

“If we missed a dropout, they’re not only dropping out of high school, they’re dropping out of life, and their ability to earn a (living),” he said. “So of course I’m concerned. I’m concerned (about) what it means for the rest of life, not just the system and its data gathering.”

When the errors were first reported in June, officials admitted there was a problem, but said they didn’t plan to go back to fix the publicly-reported statistics.

Becky Vevea is an education reporter for WBEZ. You can follow her @WBEZeducation.