Influence of data display formats on physician investigators' decisions to stop 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 unplanned 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 conducting clinical trials.

INTERVENTIONS

PARTICIPANTS were shown tables, pie charts, bar graphs, and icon displays containing hypothetical data from a clinical trial and were asked to decide whether to continue the trial or stop for an unplanned statistical analysis.

MAIN OUTCOME MEASURE

Percentage of accurate decisions with each type of display.

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 unrelated to the actual data. In the design of clinical trials information systems, careful consideration should be given to the method by which data are framed and displayed in order to reduce the impact of these extraneous factors.