One of the most popular statistical graphs is the scatterplot which we use to visualize relationships between two quantitative variables. Although a scatterplot is a common plot in our introductory statistics class, I think we overestimate our students’ abilities to actually understand the patterns that we’d like them to see.
I just read an interesting blog which talks about the difficulty in interpreting scatterplots.
At the graduate level, I find that students generally have difficulty in interpreting residual graphs. It probably means that they haven’t had sufficient experience in reading residual graphs.