[tomtheelder]

I recognize that this is just anecdote v. anecdote, but from TA-ing a number of college courses I have found the correlation between attendance and grades to be extremely strong. There are undoubtedly exceptions such as yourself and your friends- interestingly I myself was such an exception as an undergrad- but in general students with better attendance seem to get better grades.

_That said_, I suspect that this effect is almost entirely attributable to lurking variables such as discipline and interest. A lot of students with poor attendance are either students with poor work habits, or ones don't care about the course. Both of those tend to produce poor grades. The study cited addressed study habits, and maybe touched on interest a little, but It's hard for me to say exactly how well they adjusted for those since it's paywalled.