Three in every four teachers were effective in Florida classrooms last year, but 2 percent need improvement, according to a state report released Wednesday.

The report offered the first glimpse of how the state’s new controversial evaluation system graded teachers in 2011-12. The system combines a test score-driven, statistical formula with traditional principal observations.

But the report is preliminary and far from conclusive in judging teacher performance -- or how well the new system is working.

In fact, there was at least one mistake in the report -- some teachers in Hillsborough County were counted twice -- that prompted administrators at the state Department of Education to take the report off its website to double-check information. Cynthia Sucher, the DOE’s communications director, said Hillsborough officials alerted the state that the number of teachers listed was greater than the actual number of teachers employed. Sucher said the department “reviewed all records and found duplicate reporting in some other district reports, as well.” She couldn’t say how many or where, but that an updated report was expected to be available Thursday.

“We feel comfortable that we got it now. But we don’t want to take a chance, so we’re going through it with a fine-tooth comb,” she said.

The incident echoes what happened over the summer, when the state released school grades, but later had to correct more than 200 because state administrators forgot to include part of the grade formula.

Wednesday’s report on teacher evaluations did not include information on about a quarter of Florida teachers. It is missing the majority of Miami-Dade’s teachers and all of Palm Beach County’s.

Other districts’ results vary widely. Broward had nearly 92 percent of teachers rated effective, compared to 100 percent of teachers in Monroe; 55 percent in Hillsborough; and 16 percent in Leon.

In Broward, there are concerns that top teachers who instruct high-performing students are graded “needs improvement.”

Kathy Hebda, the state’s deputy chancellor for educator quality, said a final report for 2011-12 will be available in January. She attributed differences among districts to local flexibility in how student performance data was included in the system. State and district administrators showed an “abundance of caution” in the first roll-out, she said.

“Any time you do something this big, you need to do it very carefully and very thoughtfully and that’s what they’ve done,” Hebda said. “I think it is a valid instrument.”

Others disagree. Florida Education Association President Andy Ford said in a statement the incomplete report is further proof that the evaluation tool is “still not ready for prime time.”

Under the old system, there were only two grades for teachers: satisfactory and unsatisfactory. And the state received reports that less than 1 percent of Florida teachers were unsatisfactory.

The new test score-driven evaluations -- dubbed “value-added” -- were mandated by the Florida Legislature last year and combine traditional observations with student scores and other data. By the 2014-15 school year, the new evaluations will be tied to tenure and salary.