Sep
Start of Mini-Series: Randomized Controlled Trials as Tools to Understand Public Policy Decisions
(I) “Encouraging the Adoption of Agroforestry: A Case Study in Eastern Province, Zambia” (Kelsey Jack, Tufts; Paulina Oliva, UCSB; Elizabeth Walker, Harvard; Samuel Bell, Cornell)
In a quest to understand whether cashflow constraints or the absence of short-term financial benefits impede the uptake of agroforestry practices of farmers in Zambia, the research team surrounding Kelsey Jack from Tufts University in collaboration with Trees on Farms Programme conducted a randomized controlled trial in which they analyzed the effect of different subsidy and incentive schemes on farmer adoption. The subsidies took the form of different input-price reductions (from free hand-out of tree seedlings to having farmers pay their full market price) while the incentive payments were outcome-based and rewarded farmers, whose tree survival rate surpassed 70% after one season (Nov ’11-Dec ’12).
All farmers underwent training on planting and tree care before they could decide to opt into the programme for one year and receive the seedlings or not.Randomisation was implemented through a lottery (scratch cards that listed the individual rewards – randomization on the individual level) and a computer-orchestrated algorithm, that allocated input-prices at the farmer group-level (in total, 1,300 farmers are trained in 125 farm groups). Performance-incentives were revealed alternatingly either before or after people opted into the program. Data were collected at baseline, at periodic intervals at which every fifth participant was visited to observe planting progress, for a ‘planting survey’ to register the number of trees planted and at end-line to track the tree survival rate.
According to the researchers their data reveal that: