- The main explanation of their gross differences in scholastic achievement is the better social composition of private schools, both government dependent and independent. But pupils at private government-dependent schools have a higher net educational achievement than do comparable pupils at public schools with the same social composition.
- The explanation of the remaining net differences in scholastic achievement seems to be their better school climate.
- Net differences in scholastic achievement between public and private school sectors are equal across nations, despite historical differences of educational systems.
- Analysis reveals that private independent schools have lower scholastic achievement than do public schools with the same students, parents, and social composition. However, poorer learning and teaching conditions, or a more negative school climate, cannot explain this lower scholastic achievement. The explanation of their initially higher scholastic achievement is the better social composition of these schools. This better social composition increases the educational outcomes of the students of these schools significantly above the level of other types of schools.
- Private independent schools are good because they can “attract” the best means of production (students, school composition) that can sufficiently guarantee high scholastic outcomes.
- The effects of private independent and private government-dependent schools are more or less equal in the various countries in question. This means that none of these countries are exceptional regarding the deviating educational outcomes of their private independent or private government-dependent schools, whatever the historical background and origin of the nonpublic schools or their current constitutional arrangements. The higher scholastic achievement of the private government-dependent sector does not vary with the size of this sector.
- In these societies, formal and informal school choice has become an important means for mobility along the educational inequality dimensions, and private government-dependent schools, whatever their history, have on average a better school climate and thus a more or less higher net scholastic achievement.