Interesting link! I think the explanation is that homeschool parents are not providing "tutorial instruction" to their children most of the time (that's the 2

Interesting link! I think the explanation is that homeschool parents are not providing "tutorial instruction" to their children most of the time (that's the 2 sigma effect). I don't know of good statistics of actual parent behavior but from my homeschool readings it seems like parents often provide something like "reinforcement", "cues and explanations", and "student time on task". Those are 1 to 1.2 sigma effects.