Algorithms for seeding social networks can enhance the adoption of a public health intervention in urban India
https://www.pnas.org/doi/10.1073/pnas.2120742119
Targeting structurally influential individuals within social networks can enhance adoption of health interventions within populations. We tested the effectiveness of two algorithms to improve social contagion that do not require knowledge of the whole network structure.
We mapped the social interactions of 2,491 women in 50 residential buildings (chawls) in Mumbai, India. The buildings, which are social units, were randomized to (1) targeting 20% of the women at random, (2) targeting friends of such randomly chosen women, (3) targeting pairs of people composed of randomly chosen women and a friend, or (4) no targeting.
Both targeting algorithms, friendship nomination and pair targeting, enhanced adoption of a public health intervention related to the use of iron-fortified salt for anemia. In particular, the targeting of pairs of friends, which is relatively easily implementable in field settings, enhanced adoption of novel practices through both social influence and social reinforcement.
We confirmed previous results obtained by our group on the effectiveness of the friendship nomination strategy in Honduras (13). The present study demonstrates the effectiveness of friendship-nomination targeting in an entirely different context, moreover one focused on new product adoption rather than promotion of a more general behavioral change with existing products. More importantly, a pair-targeting strategy was introduced and tested here in order to address cases where friend nomination may be infeasible despite its effectiveness, for instance, when it may be unethical not to offer the intervention to a random seed while delivering the same beneficial intervention to his or her friend. A further advantage to the pair strategy is that it can be implemented to select half as many seeds and thus evaluate fewer initial households. We found that pair targeting also enhanced adoption, when compared with random targeting, and that pair targeting was no less effective than friend targeting.
- D. A. Kim et al., Social network targeting to maximise population behaviour change: A cluster randomised controlled trial. Lancet *386*, 145–153 (2015).