Working Papers

Social Signaling and Childhood Immunization: A Field Experiment in Sierra Leone [Job Market Paper]

Individuals care about how they are perceived by others, and take visible actions to signal their type. This paper investigates social signaling in the context of childhood immunization in Sierra Leone. Despite high initial vaccine take-up, many parents do not complete the five immunizations that are required in a child's first year of life. I introduce a durable signal - in the form of differently colored bracelets - which children receive upon vaccination, and implement a 22-month-long experiment in 120 public clinics. Informed by theory, the experimental design separately identifies social signaling from leading alternative mechanisms. In a first main finding, I show that individuals use signals to learn about others' actions. Second, I find that the impact of signals varies significantly with the social desirability of the action. In particular, the signal has a weak effect when linked to a vaccine with low perceived benefits and a large, positive effect when linked to a vaccine with high perceived benefits. Of substantive policy importance, signals increase timely and complete vaccination at a cost of approximately 1 USD per child, with effects persisting 12 months after the roll out. Finally, I structurally estimate a dynamic discrete-choice model to quantify the value of social signaling.

Social Signaling and Prosocial Behavior: Experimental Evidence in Community Deworming in Kenya (with Karim Naguib)

Can social image concerns motivate adults to internalize health externalities? In collaboration with the Kenyan Government, we implement a new community program that offers free deworming treatment to 200,000 adults and emphasizes the public good aspect of deworming. Importantly, we randomize the introduction of two types of social signals in the form of colorful bracelets and ink applied to the thumb. The bracelets and ink allow adults to signal that they contributed to protecting their community from worms. To separate social signaling preferences from reminder and learning effects, we offer free text messages to a random subset of adults. Further, we exogenously vary the travel distance to treatment locations. We find that (1) bracelets as signals increase deworming take-up by 24 percent, outperforming a material incentive; (2) the effects are not due to pure reminder or learning effects; (3) there is no detectable effect for the ink signal, which we attribute to its lower visibility; (4) adults are highly sensitive to distance and both signaling treatments have a larger impact on take-up at far distances. The latter finding is consistent with the theoretical prediction that signaling returns increase as signals become more informative. Detailed survey data on first and second-order beliefs shed light on the underlying mechanism: signals reduce information asymmetries, and adults are more likely to think that others have information about their deworming decision.

Works in Progress

“Social Signals for Prenatal Care and Safe Delivery: A Field Experiment in Sierra Leone” (Fieldwork complete) [Project Description]

“Externalities and Social Influence in Childhood Immunization” (Pilot in Pakistan complete) [Project Description]