The Design of Ballantines.
WASHINGTON UNIV SEATTLE DEPT OF PSYCHOLOGY
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The widespread availability of computational graphics for personal computers has greatly increased the potential for visual displays of data. The display of pairwise correlations between two and three variables is of special interest to psychologists. To motivate the subsequent development, consider a case that arose in our own laboratory. College students participated in three tasks, an auditory dichotic listening task, a visual scanning task, and an arithmetic task. Our interest was in the extent to which variance was shared between pairs of tasks, with some portion of the variance in the third task held constant. Part and partial correlations may be used to express the statistical relations. However this method of summarization was not appropriate for verbal presentations of our results, especially to audiences who were not familiar with advanced methods of correlational analysis. An alternative to the statistical summary is to use a visual display, in which the variance of each variable is represented by a circle. Shared variance is represented by the overlap between two circles. If three variables are represented the resulting figure is called a ballantine. The ballantine is a useful display of shared and unique variance because each component of variance can be identified visually in the geometric form.
- Statistics and Probability