Influence of data display formats on physician investigators' decisions tostop clinical trials: prospective trial with repeated measures

Objective To examine the effect of the method of data display on physician investigators' decisions to stop hypothetical clinical trials for an unplan ned statistical analysis. Design Prospective, mixed model design with variables between subjects and within subjects (repeated measures). Setting Comprehensive cancer centre. Participants 34 physicians, stratified by academic rank, who were conductin g clinical trials. Interventions Participants were shown tables, pie charts, bar graphs, and i con displays containing hypothetical data from a clinical trial and were as ked to decide whether to continue the trial or stop for an unplanned statis tical analysis. Main outcome measure Percentage of accurate decisions with each type of dis play. Results Accuracy of decisions was affected by the type of data display and positive or negative framing of the data. More correct decisions were made with icon displays than with tables, pie charts, and bar graphs (82% v 68%, 56%, and 43%, respectively; P = 0.03) and when data were negatively framed rather than positively framed in tables (93% v 47%; P = 0.004). Conclusions Clinical investigators' decisions can be affected by factors un related to the actual data. In the design of clinical trials information sy stems, careful consideration should be given to the method by which data ar e framed and displayed in order to reduce the impact of these extraneous fa ctors.