I'm surprised they didn't try to get data on students who didn't take any notes at all. Back in the 90s I irritated quite a few college teachers by not doing any note taking - my ability to do handwriting has always been terrible and I absorbed much better by not doing it and then latching on to my friend's notes. Later on, taking notes on laptops proved a much better experience, and these days it's Markdown for the best results / effort (if I needed heavy math I'd have probably learned LaTex).