The survey covered producers in the handricraft, horticulture, and dairy value chains in the Northern Zone. On average, producers in the handicraft, horticulture, and dairy chain were 40, 45, and 50 years old, respectively.
For each value chain, a few weeks prior to the start of the first cycle, Chemonics provided Mathematica with lists of potential beneficiaries required for each value chain. The number of potential beneficiaries on these lists was determined by Chemonics' target number of participants for each implementation cycle, as well as Mathematica's preliminary calculations of the size of the impacts that the evaluation would be likely to detect with those sample sizes. Within the lists, producers were organized by groups -- either the groups in which they already worked or new groups organized by Chemonics for training and assistance purposes.
Then, for each value chain, Mathematica randomized the set of potential beneficiaries into two groups: the treatment group, which would be served in the first cycle, and the control group, which would be served in the second cycle. Groups and individuals designated as exceptions by Chemonics were excluded from randomization. Mathematica sent the randomized lists of assigned potential beneficiaries to Chemonics, and Chemonics informed producers of the start-date of their services.
Baseline and follow-up surveys had response rates above 89 percent, and treatment and control groups in the dairy chain had slightly less than 90 percent of randomized producers in the final evaluation sample.
Statistical weights cannot be used to make the evaluation results truly representative of all PBS participants. This is because the study population was not drawn randomly from the full range of geographic locations served under PBS. Furthermore, the study population was deemed to be eligible only under Phase I selection criteria, as opposed to a substantial portion of PBS beneficiaries, who met stricter Phase II eligibility standards.