There’s another bias in that kids with educated parents in public school will also have higher grades on average than the average public school kid. I don’t know how much that might affect conclusions. It doesn’t seem necessary to make the point.
I have no doubt that a private tutor can outperform a public school, but it takes a number of factors, and it’s more difficult to outperform public school combined with that same personal, educated tutor.
There’s another bias in that kids with educated parents in public school will also have higher grades on average than the average public school kid. I don’t know how much that might affect conclusions. It doesn’t seem necessary to make the point.
I have no doubt that a private tutor can outperform a public school, but it takes a number of factors, and it’s more difficult to outperform public school combined with that same personal, educated tutor.