Studies of the effects of class attendance on class performance typically are quasi-experimental because students choose whether or not to attend class; that is, the samples are self-selecting. The lack of random assignment prevents one from establishing a causal relationship between attendance and performance. Relating attendance to performance using the students in a research methods class, regardless of whether the data show a significant relationship, can serve as the basis of a discussion of quasi experiments and the alternative explanations that are inherent in their design. This article gives suggestions for presenting and discussing the data. (Contains 1 figure and 1 table.)