[mattkrause]

Yup! And the “right” way to handle that bias depends on a lot of background information/subject matter experience.

If the question were “Which musical acts do you want for the Spring Fling festival?”, it might be okay—-or even smart—-to ignore the non-responders. Including data from people unlikely to attend is probably unhelpful. If you’re asking about workloads or engagement, you certainly can’t assume that data is missing at random or the non-responses are irrelevant.

For teaching specifically, one of the smartest questions I’ve seen is “How well do you think you’re doing in this course?” The crosstabs can help address response bias.