William G. Bowen, Matthew M. Chingos, Kelly A. Lack & Thomas I. Nygren:

Online learning is quickly gaining in importance in U.S. higher education, but little rigorous evidence exists as to its effect on student learning outcomes. In “Interactive Learning Online at Public Universities: Evidence from Randomized Trials,” we measure the effect on learning outcomes of a prototypical interactive learning online (ILO) statistics course by randomly assigning students on six public university campuses to take the course in a hybrid format (with machine-guided instruction accompanied by one hour of face-to-face instruction each week) or a traditional format (as it is usually offered by their campus, typically with 3-4 hours of face-to-face instruction each week).
We find that learning outcomes are essentially the same–that students in the hybrid format “pay no price” for this mode of instruction in terms of pass rates, final exam scores, and performance on a standardized assessment of statistical literacy. These zero-difference coefficients are precisely estimated. We also conduct speculative cost simulations and find that adopting hybrid models of instruction in large introductory courses have the potential to significantly reduce instructor compensation costs in the long run.

Alex Tabarrok:

A 25% time-savings is significant. Moreover, the 25% time-savings figure is in itself an underestimate of savings since it does not include the time savings from not having to drive to class, for example.
Online education even in its earliest stages appears to be generating large improvements in educational productivity.