Bonnie Lysyk said in a report released Thursday that the overall graduation rate dropped from 75.6 per cent to 72.3 per cent between 2004-05 and 2008-09 — the latest years for which data is available. That's a drop of 3.3 per cent or 439 students.
The graduation rate for aboriginal students was lower at 32.7 per cent, although that actually represented a slight increase.
Lysyk couldn't say why the rate fell.
"We looked to the ministry to provide us that type of analysis and we weren't able to obtain it from the ministry. I think it's the ministry's responsibility to prepare that type of analysis," said Lysyk.
The auditor also said the Ministry of Education hasn't given clear direction to educators on how to turn things around.
"The ministry does not set targets for the education system. It does not have targets for improved graduation rates and does not specify what improvements it expects in student achievement."
One of her 10 recommendations is for the ministry to clearly state what should be measured and how it should be measured to assess student progress.
Education Minister Russ Marchuk said there could be many reasons for the rate drop including lack of student engagement, community or parent factors. Some students may have also left school to seek work.
Marchuk said there is cause for concern.
"We certainly need to improve our graduation rates, especially as they pertain to First Nations and Metis students, but for everybody. Seventy-three per cent is not good enough."
He said the ministry will work on the auditor's recommendation to provide more direction and targets to schools.