Biased Beliefs, Motivated Reasoning, and Consumer Valuation of Vegetable Labels in Vietnam

Last registered on November 30, 2022

Pre-Trial

Trial Information

General Information

Title
Biased Beliefs, Motivated Reasoning, and Consumer Valuation of Vegetable Labels in Vietnam
RCT ID
AEARCTR-0010541
Initial registration date
November 29, 2022

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
November 30, 2022, 4:55 PM EST

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

Locations

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Primary Investigator

Affiliation
University of California, Davis

Other Primary Investigator(s)

PI Affiliation
University of California, Davis
PI Affiliation
University of Goettingen, Germany
PI Affiliation
Hue University, Vietnam

Additional Trial Information

Status
In development
Start date
2022-12-05
End date
2023-03-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This study uses a lab-in-the-field design to assess the belief updating process for consumers when presented with varying labeling schemes that communicate food safety information in retail markets for vegetables. Vietnam offers a unique setting to evaluate how individuals update beliefs over time through consumer internalization of labeling information for several reasons. First, consumers may have had emotionally intense prior experiences that make them more likely to form biased beliefs about the overall quality of vegetables in retail markets. They might have become ill from consuming vegetables with high levels of pesticide residue or vegetables that were otherwise contaminated. Households exposed to herbicides and defoliants during the Vietnam War might also be particularly concerned about pesticide use and have biased perceptions of food safety quality in retail markets. Second, relatively few labels currently exist to signal credence qualities in Vietnam’s retail market. Three labeling schemes are of interest to this study: 1) no labels are available to signal differences in quality or food safety, 2) vegetables are differentiated by a ‘pesticide-free’ voluntary private label, and 3) vegetables are differentiated by the VietGAP certified label.
External Link(s)

Registration Citation

Citation
Kiely, Sean et al. 2022. "Biased Beliefs, Motivated Reasoning, and Consumer Valuation of Vegetable Labels in Vietnam." AEA RCT Registry. November 30. https://doi.org/10.1257/rct.10541-1.0
Experimental Details

Interventions

Intervention(s)
The study will be conducted over two waves spanning a total of two months. The first wave will include the experiment and survey questions. The choice experiment will endow participants with money and ask participants to: play a dictator game between themselves and a charity; to rank, rate, and state their willingness-to-pay (WTP) for vegetables prior to and after introduction of a food safety label (and accompanying definitions if appropriate; and to share their beliefs about the relative food safety of the vegetable options). Survey questions will assess: purchasing habits, food safety and food safety label knowledge, prior illnesses from vegetables, demographics, and exposure to chemical defoliants. The follow-up survey, conducted approximately one month later, will ask participants to recall what labels they saw during the experiment, the ranking they assigned to the vegetables after seeing the labels, and again, their willingness to pay. Participants will be properly incentivized to accurately recall their rankings but will also be given the option to state that they do not recall. This allows for individuals who engage in motivated reasoning to suppress their post-signal ranking at a personal financial cost.
Intervention Start Date
2022-12-12
Intervention End Date
2023-02-28

Primary Outcomes

Primary Outcomes (end points)
This study seeks to answer the following questions:
1. To what extent do individuals who hold biased beliefs engage in Bayesian updating or motivated reasoning in the short- and long-term when provided with varying food safety labels as signals for product quality?
2. Is there a trade-off between the comprehensiveness and accessibility of these labels in markets where consumers hold biased prior beliefs?
3. If so, can the simultaneous provision of an exact label definition increase the effectiveness of the VietGAP label by reducing biases and increasing purchases of vegetables in retail markets?
Primary Outcomes (explanation)
We will use a difference-in-differences regression model to estimate treatment effects to assess the extent to which individuals update their beliefs in the short- and long-term given information that may conflict with their prior beliefs. The dependent variables for the regression specification are as defined in subsection \ref{Variables}. We may also explore a triple difference-in-differences framework and propensity score matching given the plausibly exogenous treatment of exposure to chemical defoliants.
The main dependent variables of interest are 1) ranking, rating, WTP, and perception of food safety for vegetables pre- and post-signal, 2) recall of initial ranking, rating, WTP, and perception of food safety for vegetables at follow-up, and 3) final ranking, rating, WTP and perception of food safety for vegetables at follow-up. The main right-hand side variables include: 1) assignment to treatment or control groups, 2) prior illness or disability stemming from consumption of contaminated vegetables 3) prior exposure or to chemical defoliants or having a friend/relative who was exposed to chemical defoliants 4) vegetable purchasing habits, food safety knowledge and beliefs, and 5) basic demographic controls.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This study will be conducted in Hue City, Vietnam. This city lies in Thua Thien Hue province, one of the most heavily sprayed areas during the Vietnam War, just south of the 17th parallel. We have partnered with the Center for Knowledge Co-creation and Development Research (CKC), a non-profit that is established in Hue which has experience administering and collecting survey data in the province. The head-of-household or primary shopper for the household will be asked to participate in the experiment.

The study targets both households directly affected and unaffected by Agent Orange. Households affected by Agent Orange will be included in the pool of households that will be randomly determined to participate in the study. The total sample size is expected to be 600 households split into two treatment and control groups. The treatment and control groups are not expected to differ from one another across any observable characteristics.

Households are assigned to two control groups and two treatment groups in this experiment. A vegetable label will be displayed to the control groups while the vegetable label and definition will be displayed to the treatment groups. The definition reduces uncertainty of the quality of the labeled good. The first control group is presented with one conventional vegetable and one pesticide-free vegetable (a 'pesticide-free' label that only addresses one dimension of food safety) without a definition of the label. While the first treatment group is presented with one conventional vegetable and one pesticide-free vegetable with the label and exact definition. Similarly, the second control group is presented with one conventional vegetable and one VietGAP vegetable without a definition and the second treatment group is provided with a conventional vegetable and a VietGAP vegetable with the label and exact definition. These labels and definitions are signals that provide the individual with additional information on the food safety quality of the good. The use of the two different labels and their definitions creates variation in the comprehensiveness and accessibility of the information presented.
Experimental Design Details
Not available
Randomization Method
randomization using random sampling in Stata
Randomization Unit
wards, households
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
23 wards
Sample size: planned number of observations
600 households across 23 wards
Sample size (or number of clusters) by treatment arms
600 households
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
UC Davis, Office of Research, IRB Administration
IRB Approval Date
2022-10-12
IRB Approval Number
1947994-1
Analysis Plan

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