Students at Canadian private schools have more educational success than their public school peers because of their backgrounds and classmates, not the schools themselves, Statistics Canada says in a new report.

The study followed 7,142 Grade 10 students, focusing on standardized test scores in reading, math and science at age 15, as well as the educational qualifications they had earned by age 23.

Private school students had better test scores (about nine per cent higher on average) and more educational success after high school.

None of the differences, however, could be attributed to school resources and practices, Statistics Canada says.

"Two factors consistently account for these differences," the report released on Tuesday said. "Students who attended private high schools were more likely to have socio-economic characteristics positively associated with academic success and to have school peers with university-educated parents." 

Books, computers at home

The report says uncovering the cause-and-effect between private school and student success is challenging because of self-selection: wealthier families are better able to enrol their children in private schools, and private schools may have more stringent admission criteria.

Once in the school, private school students are more likely to have classmates who may exert a positive influence.

In short, students attending private schools had backgrounds that led to good grades.

"For example, compared with public school students, higher percentages of private school students lived in two-parent families with both biological parents; their total parental income was higher; and they tended to live in homes with more books and computers," the report says.

Report co-author Winnie Chan said the study was the first time research has combined data about students and the schools themselves. The report notes that most previous studies only looked at students in isolation, then attributed any remaining academic differences to the schools. 

School resources 'not the main players'

The study said school resources and practices differed "only slightly" between public and private institutions. 

The study looked at such resources as:

  • Student-teacher ratio.
  • Annual instructional hours.
  • Number of computers per student.
  • Percentage of teachers with an undergraduate degree.

In each case, the numbers were similar. For instance, the student-teacher ratio was 17 in public schools and 17.8 in private schools.

"We are not saying that school resources are not important in school outcomes … [but] from what we see in these studies they are not the main players compared to other factors," Chan said.

About six per cent of Canadian 15-year-olds attend private school.

The province of school attendance also accounted for some of the difference in high school test scores and graduation rates, but generally not at the post-secondary level.

Data shows Quebec has the highest proportion of students in private schools — about one in five. By contrast, the Atlantic provinces have fewer than one in 100.

'A good opportunity to crow'

Paul Bennett, the director of Schoolhouse Consulting and an adjunct professor of education at Saint Mary's University in Halifax, felt there wasn't much new in the report, except for the "amazing" levels of success by the private students.

"If anything, it gives private schools a pretty good opportunity to crow," he said. In particular, he pointed to the study's finding that 35 per cent of private school students had graduated from university by age 23, compared with 21 per cent of public school students. 

Bennett believes the report puts too much stress on socioeconomic factors and not enough on teacher autonomy and effectiveness.

"The fundamental difference is the values that are being developed in the kids," he said.

What about the labour market?

The study subjects were from 1,180 schools across the country and born in 1984.

The researchers relied on a review of current and recent literature, national and international surveys and questionnaires, and student tests.

Sample sizes did not allow for a breakdown of results by type of private school, many of which are religious based.

One important question also remains unanswered, the study states: Does the academic advantage the private school students enjoy continue into the labour market?

"The higher rates of post-secondary attendance among private high school students may translate to higher lifetime earnings," the study notes.

"This effect may be amplified through peers: A social network of gainfully employed friends may improve an individual's chances of securing a well-paying job."

With files from The Canadian Press