A measurement of decreasing impatience for health and money

This paper measures deviations from constant discounting and compares these deviations for health and money. Our measurements make no assumptions about utility and do not require separability of preferences over time. In an experiment, most subjects were decreasingly impatient, but a substantial minority was increasingly impatient. The deviations from constant discounting were more pronounced for health than for money suggesting that time preferences are domain-specific. Hyperbolic discounting (Loewenstein and Prelec, Quarterly Journal of Economics, 107, 573–597, 1992) and proportional discounting (Mazur, Quantitative Analyses of Behavior, 5, 55–73, 1987) best described time preferences. Quasi-hyperbolic discounting, the most popular model to accommodate deviations from constant discounting, was rejected for both health and money.