BMJ 1999;318:1527-1531 ( 5 June )

Information in practice

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

Editorial by Wyatt

Linda S Elting, associate professor of epidemiology,  Charles G Martin, assistant professor of biomathematics,  Scott B Cantor, assistant professor of medicine,  Edward B Rubenstein, associate professor of medicine. 

Department of Medical Specialties, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard---Box 40, Houston, TX 77030-4095, USA

Correspondence and reprint requests to: Dr Elting lelting{at}mdanderson.org

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.


Key messages

  • In clinical trials formal interim monitoring points, at which statistical tests are conducted, are designated a priori, but investigators also conduct informal interim monitoring, when statistical tests are not used

  • This study investigated the effect of the method of displaying results on clinical investigators' decisions to conduct unplanned analyses of a hypothetical clinical trial

  • The method of displaying results significantly influenced the accuracy of decisions, as did the framing of these results (positive or negative)

  • The display formats preferred by the clinical investigators did not lead to the most accurate decisions

  • Careful consideration should be given to the method of data display in information systems supporting clinical research




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Rapid Responses:

Read all Rapid Responses

A sheep dressed in wolf's clothing
James M Walker
bmj.com, 5 Jun 1999 [Full text]
Data presentation is a specialised skill
Adam Jacobs
bmj.com, 5 Jun 1999 [Full text]
Mislabeled diagram
Nick Hendel
bmj.com, 18 Jun 1999 [Full text]
Influence of data display on decisions--Bar Charts in the Wrong Order?
David Jobson
bmj.com, 10 Jun 1999 [Full text]
Author's reply
Linda S Elting
bmj.com, 18 Jun 1999 [Full text]
Framing and Display formats in decisions to stop clinical trials
Jamie C Brehaut, et al.
bmj.com, 4 Nov 1999 [Full text]
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