[MrTonyD]

Recently it was discovered that working 20 hours a week while going to school results in worse grades - after decades of believing the exact opposite. When they did better studies - comparing like students (same school, same background, and other characteristics), they discovered that all the prior studies were just showing the success of students who really should have been even more successful. So I prefer to think of most studies such as this as a datapoint, rather than any type of evidence.

[icebraining]

A datapoint is evidence, just not proof.

[MrTonyD]

You might want to look up the definition of evidence. My reading of three definitions just doesn't quite match your definition. But no big deal. I think we agree, and this has become about word interpretation.