Communicating Effect Sizes to Teachers

Abstract: This study explores how various visualizations impact teachers' understanding of effect sizes and their relevance to practice. In Study 1, 40 teachers assessed four visualization types displaying six effect sizes. Half-eye plots were perceived as less challenging and more informative compared to raincloud and Gardner–Altman plots. However, misconceptions of U 3 and overlap were prevalent across all types. In Study 2, enrichment options (signaling, benchmarking) integrated into half-eye plots were examined for their impact on, among others, understanding and misconception reduction. While benchmarks increased time needed for decision-making, they did not improve accuracy compared to a control group and neither did signaling. However, both signaling options substantially reduced misconceptions. Furthermore, one signaling option increased participants' sensitivity to group differences. This study offers first indications of a promising visualization type, the half-eye plot, and an enrichment option to decrease misconceptions when considering visualization design in science communication efforts aimed at supporting educators.