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Evaluating the Socio-economic Impacts of Western Seed’s Hybrid Maize Program
Last registered on July 31, 2014


Trial Information
General Information
Evaluating the Socio-economic Impacts of Western Seed’s Hybrid Maize Program
Initial registration date
July 31, 2014
Last updated
July 31, 2014 9:56 AM EDT
Primary Investigator
University of California, Davis
Other Primary Investigator(s)
PI Affiliation
Tegemeo Institute of Agricultural Policy and Development
PI Affiliation
University of California, Davis
Additional Trial Information
On going
Start date
End date
Secondary IDs
We propose to evaluate the impact of Western Seed Company’s (WSC) hybrid maize program on the welfare of smallholder farmers in Kenya’s mid-altitude regions. This locally-based and locally focused seed company is expanding into new areas, powered by recent infusions of venture capital. By collaborating closely with WSC, we are exploiting this geographic expansion with a two-year randomization design in parts of western and central Kenya, creating well-defined treatment and control groups. Because of differences between western and central Kenya, we expect the constraints, and ultimately the impacts in these two regions to be different. In particular, the western region is poorer, and farmers there are unlikely to reap the full benefits of WSC technologies in this liquidity-constrained environment. We will therefore also relax these liquidity constraints for some farmers in the western area by providing fertilizer, randomized at the household level. In summary, we hope to learn about two key issues: the effectiveness of a local seed company in developing technologies fine-tuned to the local agro-ecological environment, and the impact of relaxing liquidity-constraints on the poverty-reduction potential of new agricultural technologies.
External Link(s)
Registration Citation
Carter, Michael R, Travis Lybbert and Mary Mathenge. 2014. "Evaluating the Socio-economic Impacts of Western Seed’s Hybrid Maize Program." AEA RCT Registry. July 31. https://doi.org/10.1257/rct.443-1.0.
Former Citation
Carter, Michael R et al. 2014. "Evaluating the Socio-economic Impacts of Western Seed’s Hybrid Maize Program." AEA RCT Registry. July 31. http://www.socialscienceregistry.org/trials/443/history/2267.
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Experimental Details
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Adoption of improved hybrid maize seeds (Western Seed Company in particular)
Income (agricultural, non-ag)
Land use (type of crop, in particular proportion of land allocated to maize)
Food security
Dietary diversity
Progress out of Poverty Index (PPI)
Educational completion rates & educational expenditures
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The main treatment arm provided treated households in treatment villages with access to (i) a Western Seed demonstration plot, (ii) an information session about Western Seed hybrid maize varieties, and (iii) a 250g sample pack of Western Seed hybrid maize seeds. The treatment was cluster-randomized to 36 clusters (18 T, 18 C) with 1,800 farm households spread across 3 (randomly selected) villages per cluster. The second treatment arm was randomized at the household level and provided a 50 kg bag of blended fertilizer, appropriate for the sample farmers' soils.
Experimental Design Details
Randomization Method
The first level of randomization was done in an Excel spreadsheet (the clusters were paired by some basic characteristics (basic geography, agro-ecology/altitude/rainfall), and one cluster in each pair was chosen for treatment and one for control. This randomization selected demonstration plots (control 'demo plots' were excluded and no demo plot was arranged at that site).
Within a 5-km radius of these demonstration plots, local administrative officials listed the villages within the radius, and 3 villages were chosen for inclusion in the sample. Further, village officials listed all households in the village. From the population of these clusters of 3 villages, households were selected proportional to the size of the village, such that 50 households were spread across the 3 villages.

The fertilizer randomization was conducted publicly. The names of all sample households were placed in a bucket and drawn in front of a gathering of said households. The lottery 'losers' were given a $5 airtime voucher, while the 'winners' received 50kg of fertilizer.

Note that the fertilizer treatment only took place in western Kenya.
Randomization Unit
Please see previous field (clusters for information-treatment arm; household-level for fertilizer-treatment arm)
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
36 demonstration plots, with 3 villages around each.
Sample size: planned number of observations
1,800 households
Sample size (or number of clusters) by treatment arms
Please see attached image in supporting doucmentation (obs_per_treatment_group.jpg)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Using the TAPRA data, collected by Tegemeo Institute in 2010, our power calculations suggest the following Minimum Detectable Effects (MDEs): in Western/ Nyanza, δ_yield∈ (0.5, 0.3) and δ_income∈ (0.4, 0.3), where δ denotes the standardized effect size.* Given the means and standard deviations of yield and income respectively, this translates into MDEs for yields of 15-26% of the average 2010 yield, and 25-35% of the average 2010 household income, depending on the amount of variation in the outcome variables that can be explained by baseline values of covariates.** In Central/Eastern, δ_yield∈ (0.6, 0.45) and δ_income∈ (0.6, 0.45), implying MDEs corresponding to 30-35% increases in yields and incomes. These should be conservative estimates of MDEs, as they are calculated using formulas for a 3-level cluster-randomized trial, while the liquidity treatment arm will be randomized at the individual level. * Using Optimal Design’s notation, the statistics used for power calculations in Western/Nyanza province are as follows: n (the number of households in each village) in each treatment arm is 9 (17 households are sampled in each village, but that number will be halved by the voucher-treatment); J (the number of clusters per site) equals 3, and there are 24 sites, K; the intra-class correlations for level-2 and level-3 in Western are ρ_π=0.083,ρ_β=0.072 (yields) and ρ_π=0.059,ρ_β=0.043 (income). In Central/Eastern, n=17, J=3, K=12, ρ_π=0.085,ρ_β=0.076 (yields) and ρ_π=0.09,ρ_β=0.07 (income). ** In the TAPRA panel data, level-3 covariates from the previous round explain between 15-40% of the variation in current-period outcome variable.
Supporting Documents and Materials

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IRB Name
Institutional Review Board, University of California, Davis
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)