In other news, the Pope is Catholic

I came across this meta-analysis of studies of the effect of class attendance on college grades.  A meta-analysis is not a single study, but rather a statistical analysis of a large body of studies.  Any one study might find a given result for any number of reasons.  However, by comparing many studies one can get an idea of whether there are any consistent findings, and put outliers in context.  That's what a meta-analysis is.  In short, these authors find that class attendance is an excellent (not to be confused with "perfect") predictor of college grades, even better than test scores and high school GPA.  Also of interest, attendance is a better predictor than personality traits (aka "non-cognitive traits"), throwing cold water on occasional claims that track record matters less than potential as evidenced by non-cognitive traits.