Previous research on perception of correlation of scatterplots used scatterplots as stimuli and asked participants to estimate or compare correlations of those scatterplots. This literature has shown a tendency for people to underestimate correlation in some correlation ranges. We flipped the task: instead of estimating correlation from visual stimuli, participants drew a scatterplot based on a given correlation: 0, 0.25, 0.5, 0.75 and 1 using 20 dots. Participants drew greater correlations for r = 0.25 and r = 0.5 (0.59 and 0.71 respectively), which is analogous to underestimating correlation in previous viewing tasks. Drawn correlations for r = 0, 0.75 and 1 were more accurate. The number of statistics courses taken did not improve correlation drawing accuracy in a strong or meaningful way. We discuss possible interpretations of these results and future directions.

Bar graphs are commonly used graphs, but what do students infer about the data that created the bar graph? Previously, a drawing task revealed that a minority of students conflate mean bar graphs with count bar graphs and draw all data points within the bar of a mean bar graph (bar tip limit error, BTLE). The present study extends this literature by manipulating the instructional text for the drawing task, interviewing the participants on their drawings, and recording their drawings and drawing session for further analysis. While we did not see any differences in the BLTE rates across instructional conditions, we did see significant differences in their drawing explanations and drawn data distributions based on condition, and in their drawing explanations based on whether they expressed confusion and whether they committed the BTLE. We discuss possible explanations and their implications.