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OTTUMWA, IOWA -- Many times, schools graduation rates and dropout rates do not equal 100%. 

In honor of graduation season, our Fact Finder team wanted to know how graduation rates are calculated.

The Iowa Department of Education adopted a formula by the National Governors Association.

By identifying each first year ninth grader with a number, this formula helps track students who graduate early or transfer to another school district.

The formula takes the number of on-time graduates divided by the number of first time 9^th graders four years prior and adjusted to the number of transfer students in and out.

2009 marked the first time a full set of data was compiled in Iowa. Therefore, comparing 2008 and 2009 data is not comparing “apples to apples” and does not show an accurate change. 2010 data is not yet available, but will provide accurate data sets.

In 2005 the governors of all 50 states agreed to voluntarily implement this formula. However, only 20 states are currently using it. The goal is to have all 50 states using this formula by 2012.

For more information on the fomula, click here or for even more details here.

To see Iowa's 2009 graduation rates, click here.