WHO GOES TO THE GYM? EVIDENCE FROM THE PRINCETON STUDENT BODY

Abstract

Hyperbolic discounting leads individuals to put off onerous activities like exercise more than they would like to from a prior perspective. This paper tests whether present-biased time preferences correlate with gym-going behavior. First, the sensitivity of individual time preferences to outcome size and time delay framing is evaluated using hypothetical choice and matching experiments. Time preferences are elicited in a controlled, laboratory setting and then matched to individuals' future gym attendance predictions and actual attendance data tracked over a one week period. The results reveal novel linkages between outcome sizes and parameter estimates of time-inconsistency, while estimates are relatively robust to differences in time delay framing. A clear, first-order stochastic relationship is observed for discount factors between the larger reward and smaller reward condition using both elicitation methods. On average, regular gym-goers are less likely to overpredict their future gym attendance, but surprisingly, preexisting levels of exercise frequency is positively correlated with overprediction. Curiously, some of the results indicate that present-biased individuals are less likely to overpredict their future gym attendance, suggesting possible evidence of sophistication.