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Spillovers of Payments for Ecosystem Services: Follow-up of a RCT in Uganda
Last registered on January 16, 2020


Trial Information
General Information
Spillovers of Payments for Ecosystem Services: Follow-up of a RCT in Uganda
Initial registration date
October 02, 2019
Last updated
January 16, 2020 8:24 AM EST
Primary Investigator
Osnabruck University
Other Primary Investigator(s)
PI Affiliation
Utrecht University
PI Affiliation
Osnabruck University
Additional Trial Information
On going
Start date
End date
Secondary IDs
Under the proposed study, we will investigate the long-term impacts of a Payments for Ecosystem Service (PES) scheme that was implemented between 2011 and 2013 in western Uganda. The PES scheme was implemented as randomized control trial in 121 villages (
RCT ID AEARCTR-0000047). A follow-up study will be conducted with both forest owners, who were eligible for PES, and additional non-forest owners. In particular, following impacts will be investigated: a) whether PES affect the propensity to engage in pro-environmental behavior in the long-term, as well as environmental attitudes and beliefs; b) whether PES changed the sharing of forest resources and access to privately owned forests at the community level; c) whether PES affect social preferences, in particular spiteful behavior, between community members, d) whether human-wildlife conflicts increased due to the intervention and how attitudes towards chimpanzee conservation were affected and e) whether the intervention changed the influence of the take-up rate at the village level on individual PES enrollment decisions (hypothetical).
External Link(s)
Registration Citation
de Laat, Joost, Stefanie Engel and Tobias Vorlaufer. 2020. "Spillovers of Payments for Ecosystem Services: Follow-up of a RCT in Uganda." AEA RCT Registry. January 16. https://doi.org/10.1257/rct.4714-1.1.
Sponsors & Partners

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Experimental Details
In the treatment villages, Chimpanzee Sanctuary and Wildlife Conservation Trust (CSWCT) staff members offered an incentive contract to each household that owned forest land, under which they will receive annual payments if they meet certain terms. Landowners are required to refrain from cutting trees on their land (with some exceptions built into the contract) and also to re-forest a portion of their land. CSWCT employees monitor compliance with the contract by conducting random spot checks in the forest to look for newly cleared patches of forest or fresh tree stumps and to assess if new trees have been planted.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
1) social preferences
2) environmental preferences
3) forest sharing behavior
4) social norms related to forest sharing behavior
5) human-wildlife conflicts
6) attitude towards chimpanzee conservation
7) hypothetical enrollment in a PES program

The primary outcomes are planned to be analyzed in separate publications. Paper 1: Outcomes 1, 3, 4; Paper 2: Outcome 2; Paper 3: Outcome 5,6; Paper 4: Outcome 7
Primary Outcomes (explanation)
1) elicited through three binary decisions for resource allocation between 2 participants to identify social preferences types;
2a) decision between six seedling packages with varying compositions of eucalyptus and native tree species (eucalyptus representing the less environmentally-friendly option)
2b) self-reported tree planting within last 12 months (yes, no, type of species, reasons for planting)
3a) self-reported access restrictions of forest owners and non-forest owners
3b) framed-field experiment (2 players: 1 forest owner, 1 neighbor) concerning forest access and resource appropriation
4) incentivized elicitation of social norms regarding forest access restrictions
5) frequency of wildlife sightings, crop and livestock damage by wildlife
6) agreement with statements concerning chimpanzee conservation
7) hypothetical PES enrollment under varying payment levels and take-up rates at the village level
Secondary Outcomes
Secondary Outcomes (end points)
1) Environmental attitudes
2) Locus of control (environmental conservation)
3) Perceived forest benefits and costs
4) Motivations for tree planting

All secondary outcomes are analyzed for Paper 2.
Secondary Outcomes (explanation)
1) index of self-reported survey items
2) index of self-reported survey items
3) number of forests benefits and costs listed in open question
4) index of self-reported survey items
Experimental Design
Experimental Design
One hundred and thirty-six villages in the Hoima and Kibaale districts of Uganda were randomly assigned to either the treatment or the comparison group. Households in both treatment and control groups received a baseline questionnaire prior to the PES program being implemented. Additionally, pre-intervention high-resolution QuickBird satellite images were taken of the study area. Boundaries of land parcels were demarcated with handheld GPS units and netbook computers and linked to the remote-sensing images to create images of and measures of the forest cover on each household’s land. Endline data collection, including both a household survey and Quickbird satellite images, will be conducted after the intervention has been implemented for two years.
The follow-up survey collects additional outcome measures that have not been collected in the household surveys before (neither baseline nor endline). The follow-up study therefore applies a cross-sectional experimental design, harnessing the random allocation of the treatment as an instrument.
Experimental Design Details
Randomization Method
In each subcounty, public lotteries were conducted to select which of two stratified groups of villages received the PES program.
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
original RCT: 136 villages, follow-up: 121 villages
Sample size: planned number of observations
1210 land owners in total: 726 forest owners (at the start of the intervention), 484 neighbors of forest owners
Sample size (or number of clusters) by treatment arms
121 villages: 60 treatment, 61 control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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IRB Name
Innovations for Poverty Action IRB
IRB Approval Date
IRB Approval Number
IRB Name
Mild May Uganda Research & Ethics Committee (MUREC)
IRB Approval Date
IRB Approval Number
Analysis Plan

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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)