According to a new federally mandated calculation for the graduation rate released by the state today, Rockdale County Public Schools’ graduation rate was slightly under the state average.

Previously, RCPS had reported a graduation rate average higher than the state and had been recording steady gains in the graduation rate since 2006.

The prior calculation method Georgia used was the Leaver rate calculation method, which included students who made up credits or completed school in more than four years. The new calculation method, known as the adjusted cohort rate, counts how many students complete high school in four consecutive years. The new method will allow states to compare graduation rates across the country.

Georgia’s Department of Education calculated an average state-wide graduation rate of 67.4 percent for 2011 under the new method. Under the previous method, it had reported a graduation rate of 80.9 percent.

Rockdale County Public Schools had a 2011 graduation rate of 66.2 percent under the new method. Under the previous method, it had recorded the highest ever graduation rate of 86 percent.

Heritage reported the highest average graduation rate under the new method, 69.79 percent, followed by Salem at 65.52 percent and Rockdale County High School at 65.07 percent.

RCPS Superintendent Dr. Samuel King said in a released statement, “We anticipated the difference in the lever and cohort graduation rates released today by the Georgia Department of Education. We are reviewing the indicators for the new formula and will remain diligent with our efforts to keep students on track to graduate on time, as well as ensuring those who need a little extra time will ultimately graduate and not drop out of school altogether.”

State Superintendent Dr. John Barge had warned of the appearance of a drop with the upcoming graduation rate adjustment when he visited Rockdale Career Academy last October.

“We’ve known for some time and communicated that this new formula would show a lower graduation rate than the rate under the previous formula,” Barge said Tuesday in a released statement. “However, regardless of calculation formula, the state has significantly raised graduation rates over the last several years, but there is still much work to do."

“The new formula provides a more accurate, uniform look at how many students we are graduating from high school,” said Barge. "I believe that in order to tackle a problem you have to have honest and accurate data. We will be able to use this new data as a baseline to see how our important initiatives are impacting graduation rates in the future.”

Tara N. Tucci, a senior research and policy associate at the Washington-based advocacy group Alliance for Excellent Education, said, “It's important that it gets out that these drops aren't the result of a state doing worse. Now we have an accurate picture."

Historically, states have calculated graduation rates using varying methods, creating inconsistent data from one state to the next. The new calculation means that the graduation rate may appear dramatically different even if the number of students who actually graduate hasn't changed.

Momentum for all states to produce a comparable four-year graduation rate began in 2005 with the leadership of the National Governors’ Association. Governors of all 50 states made a commitment to a common method for calculating each state’s high school graduation rate by signing the Graduation Counts Compact.

The primary difference in calculating the new graduation rate from the state’s current method is in the definition of the cohort.

The new “four-year adjusted cohort graduation rate” defines the cohort based on when a student first becomes a freshman. The rate is calculated using the number of students who graduate within four years and includes adjustments for student transfers.

In contrast, Georgia’s current graduation rate calculation defines the cohort upon graduation, which may include students who take more than four years to graduate from high school. Over the past five years, the state’s traditional graduation rate has gradually increased, rising from 70.8 percent in 2006 to 80.9 percent in 2011.

The new rate, which also includes subgroups, will be used for federal accountability purposes this school year. However, Georgia has received approval from the U.S. Department of Education to use a five-year cohort graduation rate for 2012.

“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,” said Barge. “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.”