There have been many innovative teaching methods tried from time to time. Twenty years ago was Calculus reform, now is flipped classrooms. We also have a resurgence of the Moore method under the name of IBL. Those are the ones I am most interested in.

Universities have had computerized grade information for twenty years perhaps. I assume it should be relatively easy to do longitudinal studies to determine the relative efficacy of these various methods. Are there such studies? Where are they? Where is the data? What are the conclusions?