Estimating Consumer Preferences for and Valuation of Fermented Milk in Senegal

Last registered on March 06, 2024


Trial Information

General Information

Estimating Consumer Preferences for and Valuation of Fermented Milk in Senegal
Initial registration date
February 22, 2024

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 06, 2024, 3:13 PM EST

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



Primary Investigator

Purdue University

Other Primary Investigator(s)

PI Affiliation
Purdue University
PI Affiliation
Purdue University
PI Affiliation
Purdue University

Additional Trial Information

On going
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Milk and milk products serve as vital sources of nutrition, particularly rich in calcium essential for bone health. Amidst rising consumption, concerns persist regarding microbial contamination, especially in fermented milk products. In Senegal, informal milk processors commonly employ suboptimal practices, while powdered milk imports dominate the market, lacking transparency in labeling. To address these issues, we conducted a randomized controlled trial (RCT) in Dakar, Senegal, to assess consumer preferences for fermented milk safety labeling and origin. Our study aims to determine consumers' willingness-to-pay (WTP) for tested versus untested and for local versus imported fermented milk, examining socio-economic influences. Targeting urban fermented milk consumers, our RCT involved 800 participants across four markets. Using the Becker-DeGroot-Marschak (BDM) auction method, we elicited bids for different milk types, considering labeling information. Our findings shed light on consumer preferences amidst safety concerns and market dynamics, particularly concerning small-scale urban processors. This study contributes to filling critical gaps in the literature and informs policy and industry practices in the local dairy market.
External Link(s)

Registration Citation

Bauchet, Jonathan et al. 2024. "Estimating Consumer Preferences for and Valuation of Fermented Milk in Senegal." AEA RCT Registry. March 06.
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Experimental Details


Our research aims to support the milk value chain in Senegal by determining what aspects consumers prioritize when purchasing fermented milk. Our goal is to gain a clearer understanding of how consumers perceive the safety of fermented milk, whether it's made from locally sourced milk or imported milk powder. In this context, local milk pertains to milk produced by Senegalese cows, while imported milk refers to milk derived from foreign cows and processed into powder before being shipped to Senegal. To achieve this, we conducted an experimental auction involving randomly selected consumers in Dakar. We will assess their demand for four variations of fermented milk: 1) no food safety certification, labeled imported; 2) certified and tested for microbial contamination, labeled imported; 3) no food safety certification, labeled local and; 4) certified and tested for microbial contamination, labeled local.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Willingness-to-pay for each type of labeled milk
Primary Outcomes (explanation)
Using the Becker-DeGroot-Marchak (BDM) incentive-compatible auction method, the respondent will be asked to bid their willingness-to-pay for each type of fermented milk against a random number. The bids will be used a measure of: i) demand for imported fermented milk, ii) demand for imported fermented milk deemed safe, iii) demand for local fermented milk, and iv) demand for local fermented milk deemed safe.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We randomly selected 800 fermented milk consumers in four local food markets in Dakar, the capital of Senegal, to participate in our experimental auction for different types of fermented milk. We established several kiosks in those markets where our surveyors randomly approached marketgoers and invited them to participate in our study. In our recruitment efforts, we strived to achieve an equitable balance between men and women participants to ensure a diverse and representative sample. Participants were offered the opportunity to purchase the four distinct types of milk products, using the Becker-DeGroot-Marschak (BDM) auction mechanism. In this auction method, participants bid against a random number for each product, separately. If their bid is higher than the random number they draw, then they purchase the item at the price they drew. If the bid is lower than the price they draw, then they do not get the option to purchase the fermented milk. This method has been proven to lead to an accurate estimate of consumers’ willingness to pay because it involves the possibility of an actual purchase (depending on participants’ willingness to pay and the result of the auction).
We incorporated an additional demographic survey to gather pertinent data on consumers' characteristics, including age, gender, education, occupation, and income. These questions delve into various factors, such as taste preferences, socioeconomic components, and other elements, which may influence participants' willingness to pay for different types of milk.
Experimental Design Details
Randomization Method
Surveyors randomly approaching every third marketgoer.
Randomization Unit
The unit of randomization is the individual
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
800 WTP for imported fermented milk, 800 WTP for imported and tested fermented milk, 800 WTP for local fermented milk, 800 WTP for local and tested fermented milk
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Purdue University Institutional Review Board
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials