Debates on the benefits and disadvantages of private schooling are as perennial as daisies – and the arguments tendered to justify each viewpoint are just about as common: a more innovative educational environment on the one side; social segregation on the other.


Results from PISA offer a more nuanced perspective. Most of the reasons parents cite for sending their children to private schools (which PISA defines as schools that are locally managed, regardless of how they are funded) are true: in general, privately run schools enjoy a more advantaged student population, more material resources, fewer teacher shortages and better disciplinary climates than public schools; and students who attend private schools usually benefit from the experience – and tend to achieve higher scores in PISA. But an analysis of PISA results, highlighted in the latest issue of PISA in Focus, also shows that students from similar socio-economic backgrounds who attend public schools, particularly public schools that have a high degree of autonomy over the curriculum they offer and how their funding is spent, do just as well in PISA as students in privately run schools.


Yet the very presence of private schools in a school system could help to improve the quality of education in public schools. Since private schools have to compete among themselves to attract the best students, they have to be both efficient and innovative in how they use the resources available to them to offer inspiring courses taught by the best teachers. To remain competitive in such a school system, public schools may then have to re-consider their own approaches to education if they want to retain the best-performing students and recruit better teachers.


However, such a spill-over effect isn’t apparent in PISA results. School systems with large numbers of private schools do not necessarily score any better in PISA than those with fewer private schools. This is because the proportion of advantaged students, who generally perform well in PISA no matter what kind of school they attend, is a constant in a given school system, and because public as well as private schools can be granted high levels of autonomy over curriculum design and resource allocation.


Count on PISA to join the debate with some revealing and provocative data. After all, PISA is not your garden-variety survey.