Climate Change Beliefs and Adaptation of Cocoa Farmers

Last registered on June 08, 2024


Trial Information

General Information

Climate Change Beliefs and Adaptation of Cocoa Farmers
Initial registration date
March 25, 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
March 30, 2023, 3:32 PM EDT

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

Last updated
June 08, 2024, 9:10 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.


Primary Investigator

Brown University

Other Primary Investigator(s)

PI Affiliation
Brown Univeristy

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
There is a lack of evidence for how heterogeneous beliefs of the population may affect the effectiveness and efficiency of incentivized subsidy programs. This project seeks to expand our knowledge of smallholder farmers' beliefs and actions towards climate change by examining how adaptation strategies respond to conditional cash transfers and information drops. We study this in the context of cocoa production in Ghana, where shade level management, i.e. growing forest trees on cocoa farms, is considered an adaptive farming practice to combat climate change. With a lab-in-the-field game design, we implement three subsidy interventions to examine cocoa farmers' different adaptation decisions on shade level. Apart from the standard payment for ecosystem services (PES), providing a fixed payment directly if the quantity of input (ecosystem services) passes a threshold, we consider two alternatives: (1) variable PES, which provides variable payments according to the input levels; (3) market-based variable PES, which offers an output-based price premium that increases with the level of ecosystem services. The cost-effectiveness of these three incentivized subsidies is ambiguous given the different distributions of heterogeneous beliefs. Additionally, we interact the two variable PES treatments with an information intervention to explore the role of correcting beliefs and its impacts on the effectiveness of the two subsidies, where farmers are informed of both climate change risks and benefits of the climate-change-resilient shade-grown practice. This draft was completed and registered after baseline data collection, but prior to the analysis of any follow-up data.
External Link(s)

Registration Citation

Shu, Yunyu and Jiayue Zhang. 2024. "Climate Change Beliefs and Adaptation of Cocoa Farmers." AEA RCT Registry. June 08.
Experimental Details


The interventions seek to assess the impacts of different conditional cash transfer policies on climate change adaptation technology adoption, as well as the effectiveness of information under each policy. To address these questions, we evaluate three different conditional cash transfer policies targeting adaptation behaviors, with two of the policy interacted with an information treatment. This yields six treatment arms.

T1: Standard PES only. Participants will be offered a standard input-based PES contract, where a fixed amount of cash transfer will be paid conditional on shade level on the farm passing a certain threshold. No extra information is provided.

T2: Variable PES only. Participants will be offered a variable input-based PES contract that offers a lump-sum payment increasing in the threshold shade levels (namely, not eligible, low shade, medium shade, and high shade). No extra information is provided.

T3: Market-based variable PES only. Participants will be offered an output-based PES contract where an additional price premium is added to the prevalent cocoa price. The premium is increasing in shade levels (namely, not eligible, low shade, medium shade, and high shade). No extra information is provided.

T4: Variable PES + Information. Participants will be offered the same subsidy as in T3. Additionally, participants are informed of the rising climate change risks on cocoa production and the benefit of shade management in curbing the cocoa production decline during adverse weather conditions.

T5: Market-based PES + Information. Participants will be offered the same subsidy as in T4. Additionally, participants are informed of the rising climate change risks on cocoa production and the benefit of shade management in curbing the cocoa production decline during adverse weather conditions.

C: Control group: No subsidy nor extra information about climate change risks and benefits of the climate-change-resilient shade-grown practice is provided.

Participating in any of the subsidy programs requires an upfront enrollment fee which is non-refundable.

In each community, We will hold six lab sessions of 8-17 participants each. In each lab session, participants are invited to make shade management decisions on two cocoa farms with hypothetical growing conditions and are rewarded based on their realized gains (including both cocoa harvest and subsidy, if any) from one of the randomly picked farms. All other procedures are the same across treatment arms.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
(1) Number of forest trees and fruit trees planted in the game
(2) Number of forest trees signed up for in the Green Ghana Program 2023/24
(3) Perceived cocoa yield under different weather conditions in the game
(4) Beliefs about climate change risks, including the likelihood of abnormal weather, and the impact of abnormal weather on yield
(5) Beliefs about benefits of shade trees, measured by the marginal impact of shade trees on yield
(6) Number of tree seedlings requested and picked up in Green Ghana Day 2024 (Sefwi Bekwai only)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
(1) Willingness-to-pay (WTP) for enrollment in the subsidy program(s)
(2) Beliefs about other farmers' participation in the subsidy program(s)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Baseline surveys took place from February to March 2023 in Nkawkaw and from February to March 2024 for Sefwi Bekwai, right after the cocoa main harvest season. The interventions (described in the Intervention section) using a lab-in-the-field design were rolled out in March to May 2023 in Nkawkaw and will be rolled out in March - April 2024 in Sefwi Bekwai. Fewer days are scheduled for Sefwi Bekwai due to a smaller sample size compared to Nkawkaw.

To validate the key outcomes measured in the lab-in-the-field, we plan to distribute real tree seedlings to lab participants according to the amount they signed up for during the Green Ghana Day 2024 in Sefwi Bekwai from the end of May to early June 2024. The seedlings are free of cost and will be distributed to each community assembly place. All sign-ups are voluntary. The tree distribution is in collaboration with the Forestry Commission of Ghana, which has generously supported us with forest tree seedlings.

Data collection on the GPS coordinates of shade trees on each farmer's plots will be conducted separately pending logistics details. A follow-up survey is planned. We will track attrition along the process and use Lee bounds if attrition is imbalanced across treatment groups.
Experimental Design Details
Randomization Method
Computer software and simple lotteries
Randomization Unit
At the farmer level. We stratify the sample by (1) gender, (2) age greater than or equal to 55, (3) land size greater than or equal to 5 acres, and (4) community (20 communities in Nkawkaw and 10 communities in Sefwi Bekwai). This leads to 128 strata in Nkawkaw after dropping strata with fewer than 6 farmers; There are 80 strata in Sefwi Bekwai and the strata with fewer than 6 farmers are kept and randomly assigned to each treatment arm, to maintain a reasonable sample size.

The total number of strata in Nkawkaw was updated from 133 to 128. The update reflects the necessary sample replacement of the first 7 communities to address an implementation error in demonstrating game harvest in the control group. As a correction, the entire sample of six treatment arms in these 7 affected communities was replaced with another 6 communities following the same sample selection of large-size communities and farmers. Within these 6 new communities, we stratified the sample and randomly assigned farmers per community into six treatment arms in the same way. Consequently, 44 strata from the initial 7 communities were dropped and substituted with 39 strata from 6 new communities. This adjustment leads to slight variations in the sample size per arm.
This is updated after the experiment but before completing data collection.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
1571 farmers in Nkawkaw and 744 farmers in Sefwi Bekwai
Sample size: planned number of observations
2 observations per farmer, which leads to 3142 observations at the land level in total for Nkawkaw, and 1488 observations for Sefwi Bekwai
Sample size (or number of clusters) by treatment arms
T1: Standard PES only: 384 farmers (260 from Nkawkaw, 124 from Sefwi Bekwai)
T2: Variable PES only: 386 farmers (268 from Nkawkaw, 118 from Sefwi Bekwai)
T3: Market-based PES only: 390 farmers (264 from Nkawkaw, 126 from Sefwi Bekwai)
T4: Variable PES + Information: 375 farmers (255 from Nkawkaw, 120 from Sefwi Bekwai)
T5: Market-based PES + Information: 392 farmers (260 from Nkawkaw, 132 from Sefwi Bekwai)
Control: 386 farmers (264 from Nkawkaw, 122 from Sefwi Bekwai)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Brown University
IRB Approval Date
IRB Approval Number


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