If you have the money to send junior to a private school, he already has an educational advantage before he walks through the door, a Statistics Canada study says.

It's not that private schools educate children much better, the study suggests, but that the students whose families can afford private schools tend to already have a leg up on their public school counterparts.

StatsCan looked at 7,142 Canadian teens registered in Grade 10 in public and private high schools and then followed them until age 23.

It broke down the students' records based on standardized test scores in reading, math and science at age 15, as well as educational qualifications by age 23.

On average, the students who attended private high schools scored 8% to 9% higher on standardized tests than those in public schools. By age 23, those who had attended a private high school had also, generally, obtained higher educational qualifications.

Researchers found those from wealthier and more educated backgrounds, combined with the fact private school students were surrounded by students of the same background, accounted for half of that difference in high school and two thirds of the difference in university graduation rates.

"Students who attended private high schools were more likely to have socioeconomic characteristics positively associated with academic success," the study concludes, adding it "found that no differences in outcomes were attributable to school resources and practices."