Time in Health

The time dimension in health is assessed and/or explained using the concept of time pref erence, i.e., preferences about when things occur or the timing of an outcome. It is believed that an individual's time preference can be relatively easily measured. This paper argues that individuals' responses to time-preference-type questions may represent not only their attitudes toward the timing of events (i.e., the points in time at which they are going to occur) but also their attitudes toward other things, such as the sequence of events (i.e., the order of good and bad events over an individual's lifetime health profile). This paper explains the distinction between the time-preference and sequence-preference concepts. Using two re cent empirical studies, it demonstrates the inability to measure individuals' pure time pref erences. The implications of this empirical obstacle in the context of medical decision making and health-care program evaluation are discussed. Key words: time preference; discounting; discounted utility model. (Med Decis Making 1995;15:31-37)