Time: 4:00 pm – 5:30 pm

Date: April 11th, 2018

Place: Amphi 250

Esther DUFLO (MIT; NBER; J-PAL) – “Using gossips to spread information: Theory and Evidence from Two Randomized Controlled Trials ” joint with Abhijit BANERJEE, Arun G. CHANDRASEKHAR and Matthew O. JACKSON

Abstract:  Is it possible to identify individuals who are highly central in a community without gathering any network information, simply by asking a few people to tell us whom we seed a information with if we want it to spread widely in the community? If we use people’s nominees as seeds for a diffusion process, will it be successful? In a first “proof of concept” RCT run in 213 villages in Karnataka, India, information about opportunities to get a free cell phone or money diffused more widely when it was initially given to people nominated by others than when it was given to randomly selected people, or village elders. In a second large scale policy RCT in 517 villages in Haryana, India, the monthly number of vaccinations increased by 22% in randomly selected villages in which nominees were given information about upcoming monthly vaccination camps and asked to spread it, than when randomly selected villagers were given the same information. After presenting the results from these RCTs, we show via a simple model how members of a community can just by tracking gossip about others, identify highly central individuals in their network. Asking villagers in rural Indian villages to name good seeds for diffusion, we find that they accurately nominate those who are central according to a measure tailored for diffusion – not just those with many friends or in powerful positions.