I don't get to control the projects sent my way. I'm not allowed to "fire" customers with difficult expectations.

Hell, I've only ever fired one engineer in a 20+ year career, and that was because he was the equivalent of a violent student whom you would expel and send to juvi.

Why is it so hard to deal with the information as presented in the study. Fine, question the details or methods of the study. Offer counter evidence. The study presented evidence that good teachers can have a noticeable and measurable level of control on the output of their students. Why is dealing with evidence not the central part of this discussion?