Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We investigate heterogeneity in responsiveness to reminder letters among New York City parking ticket recipients. Using variation in the timing of letters, we find a strong aggregate response. But we find large differences across individuals: those with a low baseline propensity to respond to tickets—a natural nudge target—react least to letters. These low-response types, who incur significant late penalties, disproportionately come from already disadvantaged groups. They do react strongly to traditional, incentive-based interventions. We discuss how accounting for response heterogeneity might change one's approach to policy and how one might use our analysis to target interventions at low-response types.