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

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

Crystal Huang

PI Affiliation

IDinsight

Contact Investigator

PI Name

Rachel LuSava

PI Affiliation

IDinsight

Contact Investigator

PI Name

Caleb Gitau

PI Affiliation

IDinsight

Contact Investigator

PI Name

Calvin Mhango

PI Affiliation

IDinsight

Contact Investigator

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 (Hidden)

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

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

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