With my move to Seattle University, the opportunity has arisen to re-examine my attendance and preparation policy for class. During the past two years, I required students in all of my courses to show up on time to class and to be prepared to discuss the assigned material. If they were tardy, absent or unprepared, I deemed them absent for that class session. My rule was to withdraw a student from the course who ended up being deemed absent for more than 25% of the scheduled class sessions. Having amassed attendance and grade data for 5 courses (2 first-year courses and 3 upper-class electives) and 223 students, I couldn’t resist the temptation to figure out whether class absences affected my students’ final grades. I’ve been crunching the numbers the past few days with Stata and have been surprised by what I found.