Formats for Improving Risk Communication in Medical Tradeoff Decisions ERIKA A. WATERS Department of Psychology, Rutgers, the State University of New Jersey, Piscataway, New Jersey, USA NEIL D. WEINSTEIN Department of Human Ecology, Rutgers, the State University of New Jersey, Piscataway, New Jersey, USA GRAHAM A. COLDITZ Harvard School of Public Health, Brigham and Women’s Hospital, Boston, Massachusetts, USA KAREN EMMONS Harvard School of Public Health, Dana-Farber Cancer Institute, Boston, Massachusetts, USA To make treatment decisions, patients should consider not only a treatment option’s potential consequences but also the probability of those consequences. Many lay- people, however, have difficulty using probability information. This Internet-based study (2,601 participants) examined a hypothetical medical tradeoff situation in which a treatment would decrease one risk but increase another. Accuracy was assessed in terms of the ability to determine correctly whether the treatment would increase or decrease the total risk. For these tradeoff problems, accuracy was greater when the following occurred: (1) the amount of cognitive effort required to evaluate the tradeoff was reduced; (2) probability information was presented as a graphical display rather than as text only; and (3) information was presented as percentages rather than as frequencies (n in 100). These findings provide sugges- tions of ways to present risk probabilities that may help patients understand their treatment options. According to normative models of decision making (Baron, 1994) and common sense, patients evaluating treatment alternatives should consider not only the nature of the outcomes that may occur but also their likelihood. Yet, laypeople clearly have Portions of this study were reported as a part of the first author’s master’s thesis. An alternate version of this article was presented at the 23rd Annual Meeting of the Society for Risk Analysis. The authors acknowledge Dr. James Metz, MD, and Michael Atkinson for their assistance with this project. Address correspondence to Erika A. Waters, MS, Department of Psychology, Rutgers University, Tillett Hall, 53 Avenue E, Room 102, Piscataway, NJ 08854, USA. E-mail: waters@ aesop.rutgers.edu Journal of Health Communication, 11:167–182, 2006 Copyright # Taylor & Francis Group, LLC ISSN: 1081-0730 print/1087-0415 online DOI: 10.1080/10810730500526695 167