Using Preference Estimates to Customize Incentives: An Application to Polio Vaccination Drives in Pakistan.

This article investigates the effectiveness of tailoring incentive contracts to individual time preferences among Lady Health Workers (LHWs) engaged in polio vaccination drives in Lahore, Pakistan. Using a field-adapted Convex Time Budget (CTB) experimental design, the study elicits intertemporal discounting parameters by observing how LHWs allocate vaccination effort across two days under varying relative prices and timing of allocation decisions. Structural estimation accounts for shocks to marginal costs and probabilistic completion of vaccination targets. In a subsequent vaccination drive, half of the LHWs receive contracts individually tailored to their estimated discount factors, while others receive random or broadly assigned contracts. Results show substantial heterogeneity in time preferences, limited aggregate present bias but more pronounced within-subject present bias, and that structurally tailored contracts significantly improve the smoothness of vaccination effort over time compared to alternative broad or atheoretic policies. The study demonstrates the feasibility and predictive validity of using structural models of intertemporal preferences to design individualized incentive schemes in real-world public health settings.