Evaluating the direct and spillover effects of a poverty-targeted sanitation subsidy program in rural Ethiopia

Last registered on February 19, 2026
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Pre-Trial

Trial Information

General Information

Title
Evaluating the direct and spillover effects of a poverty-targeted sanitation subsidy program in rural Ethiopia
RCT ID
AEARCTR-0017921
Initial registration date
February 19, 2026

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
February 19, 2026, 7:50 AM EST

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

Locations

Country
Ethiopia
Region
Wolaita

Primary Investigator

Name
Kashif Ahmed
Affiliation
IDinsight
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Other Primary Investigator(s)

PI Name
Crystal Huang
PI Affiliation
IDinsight
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PI Name
Rachel LuSava
PI Affiliation
IDinsight
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PI Name
Caleb Gitau
PI Affiliation
IDinsight
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PI Name
Calvin Mhango
PI Affiliation
IDinsight
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Additional Trial Information

Status
On going
Start date
2024-10-01
End date
2026-03-31
Keywords
Behavior, Health
Additional Keywords
Sanitation
JEL code(s)
Q53
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
While market-based sanitation (MBS) has successfully expanded access for many, purely market-driven approaches often fail to reach the poorest and most vulnerable households due to significant financial barriers. To address this equity gap, we are conducting a two-arm cluster randomized controlled trial of a poverty-targeted sanitation subsidy program integrated with iDE's MBS programming in the Wolayita zone of rural Ethiopia. 104 villages (gotts) were randomly assigned to either a control group receiving status-quo MBS programming or a treatment group receiving MBS integrated with targeted financial discount vouchers for eligible poor households. Following a baseline household listing in September–October 2024, subsidies were distributed between January and February 2025. We are returning for endline data collection between mid-January and February 2026 with a sample of approximately 1,957 households. We will assess the direct and spillover effects of the subsidy intervention on key sanitation outcomes, including the ownership and usage of unshared improved latrines, and the practice of open defecation, among both subsidy-eligible and ineligible households.
External Link(s)

Registration Citation

Citation
Ahmed, Kashif et al. 2026. "Evaluating the direct and spillover effects of a poverty-targeted sanitation subsidy program in rural Ethiopia." AEA RCT Registry. February 19. https://doi.org/10.1257/rct.17921-1.0
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Experimental Details

Interventions

Intervention(s)
The intervention integrates a poverty-targeted sanitation subsidy within a Market-Based Sanitation (MBS) program. Subsidy-eligible households in treatment villages are offered discount vouchers covering approximately 60 percent of the total cost (product, installation, and transport) of an improved latrine. Households must contribute the remaining cost via a combination of cash and in-kind labor (pit digging). Subsidized products include concrete slabs with lids or Safe Toilet (SaTo) pans, and in areas with collapsing soil, the package includes a concrete ring pit lining. Both treatment and control villages also receive standard MBS programming, which includes trained sales agents, local Latrine Business Owners (LBOs), and demand creation activities.
Intervention Start Date
2025-01-01
Intervention End Date
2025-06-30

Primary Outcomes

Primary Outcomes (end points)
1. Ownership of an Unshared Improved Latrine
2. Usage of an Unshared Improved Latrine
3. Practice of Open Defecation (OD)
Primary Outcomes (explanation)
1. Verification by enumerators of a household using an improved facility (pit latrine with a completely covered slab, only one drop hole, and a washable area surrounding the drop hole) that is not shared with other households.

2. Calculated as the average percentage of household members, aged five years or older, who consistently use the unshared improved latrine owned by the household.

3. Calculated as the percentage of household members who report open defecation as their primary sanitation practice, rather than using a latrine at home

Secondary Outcomes

Secondary Outcomes (end points)
1. Short-Term Uptake
2. Co-ownership and Usage of Shared Latrines
3. Intra-household Usage by Demographic Subgroups
Secondary Outcomes (explanation)
1. Measured using routine monitoring data (tracking sales logs and verified installations via photos and GPS) up to six months post-implementation to assess immediate demand.
2. Assesses "limited" sanitation service levels, tracking co-ownership of improved latrines shared between two or more households and the usage rates of these facilities by individual family members.
3. Disaggregates usage rates to calculate specific usage patterns for female members (women and girls aged five and older), elderly members (over age 65), persons with disabilities, and children under five years of age.

Experimental Design

Experimental Design
The study is a two-arm cluster randomized controlled trial (RCT). The unit of randomization is the village (gott). A sample of 104 villages was selected from 11 kebeles in the Wolayita zone, ensuring geographic spacing (a buffer zone) so that no study village borders another, minimizing contamination. Following a household listing exercise, villages were randomly assigned to the treatment arm (MBS + Targeted Subsidy) or the control arm (MBS Only). Randomization was stratified based on baseline village-level sanitation coverage and soil conditions (collapsing vs. non-collapsing).

Within each village, a random sample was drawn to comprise the study cohort: 7 subsidy-eligible households (to measure direct effects) and up to 16 subsidy-ineligible households (to measure spillover effects). The total expected sample size is approximately 1,957 households across the 104 clusters. Primary analysis will follow an Intention-to-Treat (ITT) framework.
Experimental Design Details
Not available
Randomization Method
Stratified randomization using Stata.
Randomization Unit
Village (gott)
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
104 villages
Sample size: planned number of observations
Approximately 1,957 households
Sample size (or number of clusters) by treatment arms
52 treatment villages, 52 control villages
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
For subsidy-eligible households (7 households per cluster), the study is powered at 80% to detect a 7 percentage point increase in latrine ownership, assuming a 5% baseline in the control group. For ineligible households, the study is powered to detect an 8 percentage point difference (positive or negative spillover), assuming a 15% baseline ownership rate. Calculations account for an intra-cluster correlation (ICC) of 0.1 and a 10% attrition rate.
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Ethiopian Society of Sociologists, Social Workers, and Anthropologists
IRB Approval Date
2026-01-07
IRB Approval Number
ESSSWA/L/AA/05927/2026
Analysis Plan

Analysis Plan Documents

Pre-Analysis plan

MD5: 13589b55732817e53a224cbef9cc8db4

SHA1: 2765e957bab7717fc226b435bb848a6940762f0f

Uploaded At: February 19, 2026