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Information In Practice

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

BMJ 1999; 318 doi: (Published 05 June 1999) Cite this as: BMJ 1999;318:1527
  1. Linda S Elting, associate professor of epidemiology (lelting{at},
  2. Charles G Martin, assistant professor of biomathematics,
  3. Scott B Cantor, assistant professor of medicine,
  4. Edward B Rubenstein, associate professor of medicine.
  1. Department of Medical Specialties, University of Texas MD Anderson Cancer Center, 1515 Holcombe BoulevardBox 40, Houston, TX 77030-4095, USA
  1. Correspondence and reprint requests to: Dr Elting
  • Accepted 9 February 1999


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.


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