Understanding Correlations: Two Computer Exercises

This article describes two QuickBASIC programs that provide students direct experience with interpreting correlation scatterplots. In one program, students estimate the size of the correlation in nine randomly generated scatterplots and receive feedback about accuracy. In the second program, students plot correlations of a certain size or type (e.g., curvilinear) and receive feedback about the size of the Pearson correlation coefficient in their plots. Other features of the program include automatic truncation of range and the addition or deletion of data points to a previously prepared scatterplot. The programs can be used in classroom exercises designed to highlight factors that influence the size of a Pearson correlation coefficient.