Discrimination against people with disabilities: Evidence from medicinal plant vendors

Last registered on September 21, 2026
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Pre-Trial

Trial Information

General Information

Title
Discrimination against people with disabilities: Evidence from medicinal plant vendors
RCT ID
AEARCTR-0019647
Initial registration date
September 07, 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
September 21, 2026, 7:56 AM EDT

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
Jan Priebe
Affiliation
Bernhard Nocht Institute for Tropical Medicine (BNITM)
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Other Primary Investigator(s)

PI Name
Renate Hartwig
PI Affiliation
RWI, University of Bochum
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PI Name
Elisa Piseddu
PI Affiliation
Bernhard Nocht Institute for Tropical Medicine (BNITM)
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Additional Trial Information

Status
On going
Start date
2026-08-02
End date
2026-11-15
Keywords
Health
Additional Keywords
health care, traditional medicine, disability, discrimination, Africa
JEL code(s)
I11, I14, J14
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
In this study we assess the impact of physical disabilities – more specifically blindness – on price and quality discrimination in access to medicine in Uganda. The focus of the study will be to understand whether herbal medicine vendors treat disabled customers differently than non-disabled customers.
External Link(s)

Registration Citation

Citation
Hartwig, Renate, Elisa Piseddu and Jan Priebe. 2026. "Discrimination against people with disabilities: Evidence from medicinal plant vendors ." AEA RCT Registry. September 21. https://doi.org/10.1257/rct.19647-1.0
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Experimental Details

Interventions

Intervention(s)
The intervention consists of exogenously varying the disability status of the purchaser of herbal medicine.

Treatment arm individuals will receive the following: Dressing and behavior as blind person during shopping process for herbal plant.
Control arm individuals will receive the following: No intervention (dressing and behavior as a non-disabled person).
Intervention Start Date
2026-08-02
Intervention End Date
2026-11-15

Primary Outcomes

Primary Outcomes (end points)
I) Price of herbal plant
a. Price per gram at initial inquiry (before bargaining)
b. Price per gram at time of purchase (after bargaining)
II) Quantity of herbal plant
a. Quantity of herbal plant (gr)
b. Difference between weight (gr) stated by vendor vs weight (gr) objectively measured
III) Quality of herbal plant
a. Predicted quality score based on sensatory plant assessment
b. Authenticity of plant material (bio-chemical analysis score)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
I) Advise and consultation quality
a. Time spent with vendor (purchase talk)
b. # of advises provided on how to use herbal plant
c. Subjective assessment of treatment by vendor (e.g., friendliness)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The design rests on an audit study that uses a 2x2x2 factorial design. The principal factor varied relates to the mystery shoppers disability status (blind vs. non disabled). The other 2 factors vary a shoppers: (i) wealth level and (ii) demand pressure.
Experimental Design Details
Not available
Randomization Method
Randomization is done in field office by the principal researchers.
Randomization Unit
Factor 1 (Disability): Within vendor randomization
Factors 2 & 3 (Wealth, demand pressure): Between vendor randomization
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
500 vendors
Sample size: planned number of observations
1,000 audit visits (2 per vendor)
Sample size (or number of clusters) by treatment arms
500 audit visits displaying disabled shopper character in 500 vendors; 500 audit visits displaying non-disabled shopper character in the same 500 vendors.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
• Calculations relate to the audit study only and involve the following assumptions: means comparison with 80% power, a significance level of 0.05, and 0.8 unit standard deviations o Price data  Assumption control group mean: 1.2 USD  MDE: 0.18 USD o Quantity data  Assumption control group mean: 10 gram  MDE: 0.18 gram o Quality data (score from 0 to 10)  Assumption control group mean: 5  MDE: 0.18 units
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Makerere University, Uganda
IRB Approval Date
2026-08-29
IRB Approval Number
CoBAMS-REC-2026-1923
Analysis Plan

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