Institute for Mathematical Behavioral Sciences

Survey results on individuals' - preferences for three-year temporal sequences of survival/mortality outcomes are presented and compared to previous results on monetary outcomes. Three anomalies (Gain/Loss Asymmetry, Short/Long Asymmetry, and the Absolute Magnitude Effect) found in previous discounting research using pairwise matching questions suggested there might be preference differences when outcomes were framed as gains (lives saved) or losses (lives lost), when sequences begin now (short term) or in fifteen years (long term), or when the number of total lives involved over a three-year sequence was small (60) or large (36,000). The standard exponential discounting model would require a person to prefer to have all the lives saved in the first year of a sequence, and have no lives saved in the ensuing two years similarly, in the case of lost lives, all the lives should be lost in the last year of the sequence. Such sequences are "steeply decreasing" over time. Fewer than half of the subjects conformed with the standard discounting model. Sizable numbers of subjects ranked the constant sequence first. We also found a Gain/Loss Asymmetry: participants preferred to spread the outcomes if they were lives lost, and consolidate them if they were lives saved. Based on these results, we conclude that temporal discounting models may be inappropriate for representing the value people place on survival/mortality outcomes. Preferences for constant or increasing sequences should be considered in decision analyses and policy making, rather than presuming all people have a preference for decreasing sequences.