Framing Effects in Choices between Multioutcome Life-expectancy Lotteries

Abstract

Aim. To explore framing or editing effects and a method to debias framing in a clinical context. Method. Clinical scenarios using multioutcome life-expectancy lotteries of equal value required choices between two supplementary drugs that either prolonged or shortened life from the 20-year beneficial effect of a baseline drug. The effects of these supplementary drugs were presented in two conditions, using a between-sub jects design. In segregated editing ( n = 116) the effects were presented separately from the effects of the baseline drug. In integrated editing ( n = 100), effects of supple mentary and baseline drugs were combined in the lottery presentation. Each subject responded to 30 problems. To explore one method of debiasing, another 100 subjects made choices after viewing both segregated and integrated editings of 20 problems (dual framing). Results. Statistically significant preference reversals between segre gated and integrated editing of pure lotteries occurred only when one framing placed outcomes in the gain domain, and the other framing placed them in the loss domain. When both editings resulted in gain-domain outcomes only, there was no framing ef fect. There was a related relationship of framing-effect shifts from losses to gains in mixed-lottery-choice problems. Responses to the dual framing condition did not con sistently coincide with responses to either single framing. In some situations, dual framing eliminated or lessened framing effects. Conclusion. The results support two components of prospect theory, coding outcomes as gains or losses from a reference point, and an s-shaped utility function (concave in gain, convex in loss domains). Pre senting both alternative editings of a complex situation prior to choice more fully in forms the decision maker and may help to reduce framing effects. Given the extent to which preferences shift in response to alternative presentations, it is unclear which choice represents the subject's "true preferences." Key words: life expectancy; mul tioutcome lotteries; framing effects; preference reversal; segregated and integrated editing; prospect theory; utility functions. (Med Decis Making 1999; 19:324-338)