Using behavioural interventions to promote the adoption of improved sweetpotato varieties in Uganda

Last registered on November 15, 2023
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Pre-Trial

Trial Information

General Information

Title
Using behavioural interventions to promote the adoption of improved sweetpotato varieties in Uganda
RCT ID
AEARCTR-0012442
Initial registration date
November 06, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
November 15, 2023, 4:04 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

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Primary Investigator

Name
Julius J Okello
Affiliation
International Potato Center
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Other Primary Investigator(s)

PI Name
David R Just
PI Affiliation
Cornell University
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PI Name
Arjan Verschoor
PI Affiliation
University of East Anglia
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PI Name
Chalmers Mulwa
PI Affiliation
International Potato Center
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PI Name
Srinivasulu Rajendran
PI Affiliation
International Potato Center
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PI Name
Reuben T Ssali
PI Affiliation
International Potato Center
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PI Name
Hugo Campos
PI Affiliation
International Potato Center
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Additional Trial Information

Status
On going
Start date
2023-05-15
End date
2024-12-15
Keywords
Agriculture, Behavior, Gender
Additional Keywords
Behavioral nudges, RCT, trial packs, consumer intervention, improved varieties, adoption, smallholder farmers, sweetpotato, Uganda
JEL code(s)
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
Adoption of improved sweetpotato varieties (ISVs), particularly certified sweetpotato vines that are free from harmful pests and diseases, is disappointingly slow in sub-Saharan Africa. In Uganda, the national adoption of ISVs stands at 12% despite decades of investments in their promotion. The underlying factors could be many, including lack of awareness and knowledge about how to use the ISV, uncertainty about performance and quality attributes of ISVs, a preference for local disease and pest-infected varieties, and difficulty accessing the ISVs when needed. In recent years, researchers have explored the use of nudges to promote behavior change. In this study, we will piggyback on on-going RCT that tests the role behavioral interventions relating to nostalgia, loss aversion, and mobile phone-based text message reminders in nudging farmers to shift from using local varieties to ISVs. In the current RCT, we specifically assess the role of providing a small seed pack or “trial pack” to farmers combined with consumer intervention in form cooking and tasting the roots of the ISVs in enhancing the adoption of improved varieties. We hypothesize that behavioral nudges combined with these second-round interventions will motivate farmers to shift from using low-yielding disease and pest-infected varieties to purchased ISVs by purchasing the latter from a designated salespoints conveniently located in their neighborhoods. We also hypothesize that providing a trial pack and the consumer intervention lowers the uncertainty about agronomic performance and taste of improved varieties enhancing their adoption. To test these hypotheses, we will implement a cluster-randomized controlled trial (RCT) in Uganda involving 120 villages (clusters), with 960 households (i.e., 8 households/village) randomly selected for tracking the effects. The second round of interventions will be rolled out in the last season of the original nudge RCT that spans four consecutive sweetpotato growing seasons (i.e., two years). It will run for one year (two seasons) from June 2023 to June 2024 with baseline and end endline data collection in June-July 2023 and July 2024.
External Link(s)

Registration Citation

Citation
Campos, Hugo et al. 2023. "Using behavioural interventions to promote the adoption of improved sweetpotato varieties in Uganda." AEA RCT Registry. November 15. https://doi.org/10.1257/rct.12442-1.0
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Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2023-07-03
Intervention End Date
2024-12-15

Primary Outcomes

Primary Outcomes (end points)
Adoption and extent of adoption respectively measured by dummy (1,0) for adoption, and the quantity of vines of improved sweetpotato varieties purchased (a continuous variable) for extent of adoption.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Household food security, food consumption, and dietary diversity
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The 64 nudge villages were initially randomized into 64 treatment and 56 control villages. In each village a salespoint was set up at central location and supplied with quality vines of ISVs at the beginning of each rain season. These 64 nudge villages will be cross-randomly assigned into a treatment group that receives trial pack of sweetpotato seed (i.e., vines) and to the control group (no vines). The cross-randomization will take into account distances between villages to avoid a treatment village being very close to control – hence reducing the risk of contamination. This will result 31 villages receiving the treatment (trial pack) while 33 don’t, hence serve as control. Similarly, the 56 villages that did not receive nudge interventions (i.e., non-nudge villages) will be cross-randomized into treatment and control, again considering distances, to yield 28 treatment (trial pack recipients) and 28 non-treatment (no trial packs).

For the part of the study involving consumer cooking and tasting, through cross-randomization, 15 of the 31 nudge + trial pack villages and 14 of the non nudge + trial pack villages will participate in the consumer intervention (as a treatment). On the other hand 17 nudge only and 14 no nudge + no trial pack will not participate in the consumer intervention. The last group thus serving as pure control group. The trial pack comprised of 25 pieces (each 30-centimers long) of each of improved sweetpotato varieties. Th cooking intervention entail cooking and tasting the roots of improved sweetpotato varieties
Experimental Design Details
Not available
Randomization Method
R simR package in computer
Randomization Unit
administrative village
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
120
Sample size: planned number of observations
960 households
Sample size (or number of clusters) by treatment arms
59 treatment villages receive trial packs, 61 villages control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Power calculations for the initial nudge RCT were conducted using the R simR package. The outcome variable of interest in all calculations is the adoption of improved sweetpotato varieties (a dichotomous variable). The other outcome of interest in this study was the extent of adoption measured by the quantity of vines of ISVs purchased, which is a continuous variable. In most behavioural studies, dichotomous variables generally require larger samples to detect effects than continuous variables, hence we focused only on the binary adoption variable. We used a base rate of adoption of 9%, which implies a standard deviation of approximately 0.29. Estimates were based upon a mixed logit analysis, with households nested in villages. We assumed a correlation of adoption within a village of 0.10. An economically significant result requires an increase in adoption of approximately 20 to 25% points. We also assumed a control and one treatment condition, targeting rejection of the null that the treatment is equivalent to the control. We found that with n=1000 (100 villages, 10 households per village) we would detect an increase in adoption of 20% points with 97% probability and 15% points with 80% probability. In order to cater for potential drop-offs and missouts due to unavailability, we targeted 120 villages (clusters) with about 60 villages implementing the full program, and the balance serving as a control. We surveyed 10 randomly selected households per village to obtain more detailed information on adoption behaviour, including the use of second or third-generation seeds, demographic information, and exposure to the messaging/interventions. This allowed us to estimate the broader impact of the program, and also to examine the populations most affected. For the trialpack intervention, power analysis allows us to detect, reasonably well, the effect of trialpack with a random sample of 8 households per village. With this sample of 8 households per village in the 120 villages, and maintaining nudge treatment and control and the other parameters above, we will be able to detect a 50% effect with probability 0.73. Going with 8 households per village/cluste results in a total sample size of 960 households, for the second part of this study. As before, the outcome variable of interest is the adoption of ISVs.
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
Cornell University Office of Research Integrity and Assurance
IRB Approval Date
2023-06-21
IRB Approval Number
2110010648
Analysis Plan

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