We run a randomized controlled trial coupled with lab-in-the-field social network experiments in urban Dakar. Decision spillovers and health externalities play a large role in determining uptake of sanitation technology, with decision spillovers being largest among households that don’t receive significant subsidies. There is no evidence that social mechanisms such as social pressure, learning from others, or reciprocity explain the spillovers. We do find evidence of a fourth, non-social, mechanism impacting decisions: increasing returns to scale. As more neighbors adopt the sanitary technology, it becomes more worthwhile for other households to adopt as well.

Privatization of a public good (the management of sewage treatment centers in Dakar, Senegal) leads to an increase in the productivity of downstream sewage dumping companies and a decrease in downstream prices of the services they provide to households. We use the universe of legal dumping of sanitation waste from May 2009 to May 2018 to show that legal dumping increased substantially following privatization–on average an increase of 74%, or an increase of about 1640 trips to treatment centers each month. This is due to increased productivity of all trucks, not just those associated with the company managing the privatized treatment centers. Household-level survey data shows that downstream prices of legal sanitary dumping decreased by 5% following privatization, and DHS data shows that diarrhea rates among children under five decreased in Dakar relative to secondary cities in Senegal following privatization with no similar effect on respiratory illness as a placebo.

Subsidies are common in development policy to encourage adoption of new technologies. Evidence suggests subsidies may either increase or decrease longer-run adoption. I study the dynamics of technology adoption in response to subsidies in an urban sanitation context. The technology, a matching platform for sanitation services in Dakar, Senegal, was designed to connect households with service providers. I exploit spatial variation in exposure to short-term subsidies for septic pit desludgings through the platform. Using a neighborhood-level panel constructed from platform administrative data, I show that neighborhoods exposed to short-term subsidies continue using the platform at significantly higher levels, but this effect declines over time. Following a subsequent city-wide subsidy campaign, increased adoption re-emerges in previously-subsidized neighborhoods. I find evidence suggesting within-neighborhood spillovers are a mechanism for increased long-run adoption: new users make up a substantial fraction of the increased adoption over time in previously-subsidized neighborhoods.

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Linking producers to export markets can improve incomes and welfare, but accessing these markets requires meeting international quality standards. Contracts between producers and buyers may facilitate meeting these standards by aligning incentives, alleviating constraints, and reducing uncertainty for producers. In partnership with two groundnut farming cooperatives in Senegal, we implement a new contracting arrangement that bundles price premium certainty with training and credit for the purchase of a new quality-improving technology. We conduct a randomized experiment to test whether this contract induces adoption of the technology and improvements in production quality. Producers randomly offered the contract are significantly more likely to purchase and use the technology. In areas where quality is otherwise low due to agro-climatic conditions, producers in the treatment group produce significantly higher-quality groundnuts. We also find that producers in the treatment group increase output sales to the cooperative on average. Importantly, the new contract is significantly more effective at increasing sales to the cooperative for producers who are more reciprocal and for whom signaling reliability is more valuable.

Agricultural productivity in Sub-Saharan Africa lags far behind all other regions of the world. A long list of policy experiments has yielded more evidence on what fails than on what works. We analyze a randomized control trial of a rare scaled-up success story: One Acre Fund’s small farmer program. Much like anti-poverty “graduation” interventions, the program aims to relax multiple constraints to productivity simultaneously. We show that participation causes statistically and economically significant increases in output, yields, and profits. In our preferred specification, maize production increases by 24% and profits by 16%. We find little evidence of heterogeneous treatment effects on yields, but observe some attenuation of impacts on total output and profits at the top end of the distribution.