A recent paper by Figlio, Rush, and Yin tests the impact of going to a live lecture versus taking the same class online. They got about 300 volunteers and assigned them randomly to an online or live lecture. They find there are positive impacts of having a real live prof instead of watching the same lecture on video. Not surprisingly the biggest impacts of live lectures were on low GPA students who saw their scores increase 4 percentage points (on the typical 0-100 scale), not sure if this is surprising but a similar impact is found for male students. Although total impacts of live lectures were measured only at about 1 point.
A few other things. The class the students would be attending live was a 200 person lecture, so this isn't the type of class you would think would make a difference to see live. I wonder if you would find greater impacts if you tested the same thing on a 20 or 30person class?
Some final questions...
What are the costs differences?
What do the students think about online classes?
Does the live audience increase the performance of the prof?
h/t to Chris Blattman