According to the four-year adjusted cohort rate, Richmond County had a 54.6 percent graduation rate in 2011. Under the previous calculation, known as the “leaver” rate, it would have been 80.7 percent.
Georgia’s graduation rate was 80.9 percent under the leaver rate, but just 67.4 percent under the new formula. Columbia County’s rate was 76 percent, compared to 84.9 percent under the old calculation.
The Georgia Department of Education released the numbers Tuesday. Federal education regulations call for all states to use the adjusted cohort rate to report graduation statistics.
The biggest reason why graduation rates changed so drastically between formulas is the difference in how cohorts, or groups of students, are tracked.
The new method divides the total number of students who earned a diploma at the end of 2010-11 by the number of first-time ninth graders in fall 2007, accounting for students who transferred in and out, and died during the four years.
The leaver rate, used by all districts in Georgia, took the number of diplomas awarded in a given year and divided by the total number of 12th-graders, so the graduation rate included students who might have taken more than four years to finish.
Tara N. Tucci, a senior research and policy associate at Washington-based advocacy group Alliance for Excellent Education, said the new formula provides a more accurate representation of education in the country.
“(It is) pretty widely known to be the gold standard in the calculations,” Tucci said. “You’re setting the group of students at the very beginning of their time in high school and you’re literally following all those students through each of those four years.”
Tucci said drastic drops in graduation rates in a given school district between the two formulas can be explained by flaws in the previous method.
The leaver method essentially bloated numbers because it did not accurately reflect the number of students who dropped out before 12th grade or if a student took longer than four years to graduate. Districts with a large number of dropouts or fifth-year seniors would have a larger difference between the two formulas, and districts with fewer of those two types of students would have a smaller gap, she said.
Tucci said the change should not be seen, however, as a drop in achievement but, rather, a more accurate way of keeping track of data.
“Don’t lose hope by these numbers going down,” she said. “It really is just a change in calculation. Hopefully using this calculation … can galvanize efforts, because now we know really what we’re working with. It’s definitely causing a lot of people to pause and think about what’s really going on in their schools.”
Carol Rountree, the Richmond County school system’s executive director of student services, said that even though the new data show a lower success rate than previously reported, the figures provide a more accurate way of looking at students.
“I think it’s fair that we are all now using the same formula,” Rountree said. “To know Georgia and Richmond County is now on a level playing field with every other state in the union makes sense to me.”
The revised calculations pulled rates down at several local schools that have been working to produce more graduates through teacher training and academic programs.
George P. Butler High School, using federal Race to the Top money to improve achievement, had a drop of 41.4 percentage points with the new formula. Glenn Hills High School dropped by 40.2 percentage points, but Principal Wayne Frazier said the new formula is not a good fit for all populations.
In Columbia County, Greenbrier High fared best under the cohort rate with 891 percent, which is just 3.4 percentage points less than with a leaver calculation. Harlem High dropped 14.1percentage points, from 73.3 percent in the leaver rate to 59.2 percent using the cohort calcuation.
In Richmond and Columbia counties, which have significant transient pupil populations in large part because of a large military community, Columbia County schools Title 1 Director Lisa Soloff said the cohort rate does provide a more accurate method to gauge schools dealing with numerous transfers each year.
The move to a uniform graduation rate formula began in 2005 when the National Governors Association recommended the standard after a proposal by the National Center for Education Statistics, according to the Georgia Department of Education.
With states using different methods to calculate graduation rates, the federal government did not have consistent data to compare one state to the next.
In 2008, the U.S. Department of Education amended regulations to require all states receiving Title I funds for students in low-income households to use the cohort formula for 2010-11 calculations.
The federal education department now requires all states to use the four-year adjusted cohort method to report graduation rates.
The formula will be used for federal accountability among states and school districts, but Georgia received federal approval to use a five-year cohort rate next year for accountability purposes.
“We know that not all students are the same and not all will graduate from high school in four years, so we asked for the U.S. Department of Education’s permission to use a five-year cohort graduation rate for federal accountability purposes,” State School Superintendent John Barge said in a news release. “Ultimately, our goal is to ensure each child will graduate from high school ready to succeed in college and a career, regardless of how long it takes.”
Columbia County Bureau Chief Donnie Fetter contributed to this article.