The effects of dot/line and bar/line combination graphs on proficiency of search, evaluation, and choice of graphical format in a policy decision context

Graphs reveal complex data by displaying answers to questions concerning details, relationships, and trends (Wainer, 1992). This study evaluated combination bar/line versus dot/line graphical formats in terms of presenting information at these three search levels. The formats were explored for proficiency, time to complete, and preference when presenting information. Forty volunteer trustees of health care organizations were randomly assigned to two groups. The Graphicacy Test (Wainer, 1980) was examined as a pretest for graphic research. Neither graphicacy, education, service on a board, or financial management experience showed a significant influence. Each group read financial reports in two presentations: one in combination bar/line and the other in combination dot/line graphical format. The findings were discussed in terms of their practical application. The bar/line graph was found to be significantly better than the dot/line format for the proficient search for details, relationships, and trends when in the second presentation. The subjects evaluated the formats in terms of ease of understanding and use. After experiencing both formats, they rated the bar/line significantly higher than the dot/line for clarity, readability, accuracy and overall satisfaction. The trustees chose the combination bar/line format for presenting information in the experiment and in their own organizations.Education, Faculty ofEducational and Counselling Psychology, and Special Education (ECPS), Department ofGraduat