External and Internal Consistency of Choices made in Convex Time Budgets

We evaluate Andreoni and Sprenger's (2012) data on choices made from Convex Time Budgets (CTB) for external consistency with the Weak Axiom of Revealed Preference (WARP) relative to the pairwise choice benchmark, and for internal consistency with respect to demand, wealth and impatience monotonicity. We find that choices very frequently violate WARP; violations of all three internal measures of monotonicity are concentrated in subjects who take advantage of the novel feature of CTB by making interior choices. Wealth monotonicity violations are more prevalent and pronounced than either demand or impatience monotonicity violations. We believe that the frequency and magnitude of WARP and monotonicity violations found in Andreoni and Sprenger's (2012) data pose a serious challenge for interpreting choice patterns or estimated parameters through CTB as reflecting deep parameters of complete preferences.