Using Graphical Displays for Evaluation Data

Abstract

Graphics are widely believed to be useful ways to communicate statistical information and stimulate data analysis. Yet we often use only the most simple graphics, bar and pie charts, or tables to present data, especially with the evaluation's audcences. Little research is available to assess the effectiveness of graphical displays with evaluation audiences. Two types of graphical displays, a modified box plot and a multivariate STAR graph were compared with tables containing the same information in an experiment with five groups that comprise the audience for evaluation results. For the univariate display, the audiences for an educational evaluation were 67% accurate in interpreting evaluation results when using a graph, compared to 63% accuracy for a table. For the multivariate display, the audiences made accurate comparisons 70% of the time, but these results were bettered by those using a table (84%). However, an individual item analysis offers some guidance for designing multivariate graphics with nontech nical audiences that may be used to improve these displays.