Chen and Lin (2008) is an interesting attempt to measure the effect of students having access to PowerPoint slides before a lecture. They argue that such access leads to better learning outcomes as measured by higher exam marks. While their empirical results shed some light on students' use of PowerPoint slides, I argue that they have not succeeded in isolating the treatment effect and the correlations cannot be interpreted as causal.
Cannon, E. (2011). Comment on Chen and Lin “Does Downloading Power-Point Slides before the Lecture Lead to Better Student Achievement?” International Review of Economics Education, 10(1), 83–89. https://doi.org/10.1016/S1477-3880(15)30039-6