Consumer Preferences for Transparent Carbon-Neutral Labels: A Choice Experiment

Last registered on April 02, 2024

Pre-Trial

Trial Information

General Information

Title
Consumer Preferences for Transparent Carbon-Neutral Labels: A Choice Experiment
RCT ID
AEARCTR-0012520
Initial registration date
March 27, 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
April 02, 2024, 11:18 AM EDT

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

Locations

Primary Investigator

Affiliation
Eawag: Swiss Federal Institute of Aquatic Science and Technology & University of St.Gallen

Other Primary Investigator(s)

Additional Trial Information

Status
In development
Start date
2024-04-05
End date
2024-07-30
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This paper focuses on the impact of transparency in carbon-neutral labeling on consumer preferences and willingness to pay. In current markets, there is a proliferation of various climate labels representing different concepts but overlapping characteristics, which may lead to consumer confusion. Furthermore, theoretical evidence suggests that a proliferation of labels might promote those labels with lower environmental quality. Therefore, this study aims to empirically understand whether providing information on the percentage of CO₂ offsetting and CO₂ reduction influences consumer preferences for carbon-neutral labels. I conduct a discrete choice experiment among UK tea consumers through an online survey. I use a split sample approach, comparing consumers' willingness to pay for standard carbon-neutral labels and “transparent” carbon-neutral labels, which additionally disclose the percentage of CO₂ offsetting and CO₂ reduction. Furthermore, I examine the effect of various factors, including concerns about carbon offsetting, trust, and confusion, on consumers' preferences for standard and transparent carbon-neutral labels.
External Link(s)

Registration Citation

Citation
Ozdemir Oluk, Begum. 2024. "Consumer Preferences for Transparent Carbon-Neutral Labels: A Choice Experiment." AEA RCT Registry. April 02. https://doi.org/10.1257/rct.12520-1.0
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Experimental Details

Interventions

Intervention(s)
The intervention is "the transparency of the carbon-neutral label," which varies across three subsamples, where transparency refers to the percentage of CO₂ offsetting and CO₂ reduction.
Intervention Start Date
2024-04-05
Intervention End Date
2024-07-30

Primary Outcomes

Primary Outcomes (end points)
The primary outcomes are:
 Respondents' choices between the three choice alternatives (two tea product alternatives and a 'none of the two' option) on each choice card,
 Marginal WTP (MWTP) estimates for carbon neutral label from each subsample.
Primary Outcomes (explanation)
Respondents' choices between the three alternatives on each choice card will be coded as binary variable, where 1 indicates the chosen alternative, and 0 otherwise. Multinomial logit (MNL) and random parameters logit models (RPL) will be used to estimate the average MWTP for a carbon-neutral label from each sub-sample.
Based on the MNL model and the RPL model (where I randomize the carbon-neutral label parameter, but not the price parameter), the MWTP is obtained by dividing the negative of the carbon-neutral label's coefficient by the price coefficient. Based on the RPL model (where I randomize both the carbon-neutral label and price parameters), the MWTP is obtained through simulation.

Secondary Outcomes

Secondary Outcomes (end points)
The secondary outcomes are the MWTP estimates for organic and ethical trade labels from each subsample.
Secondary Outcomes (explanation)
The MWTP for organic and ethical trade labels are obtained following the same approach as the MWTP for the carbon neutral label.

Experimental Design

Experimental Design
The respondents are asked to consider 80 teabags of tea (or equivalently 200 grams). The main survey includes 1,200 tea drinkers, with 150 participants for pre-testing. The discrete choice experiment (DCE) includes the following choice attributes: carbon-neutral, organic, and ethical trade labels, and price. A split-sample approach is used to understand the effect of more transparent compared to standard carbon-neutral label on consumers preferences. The survey is hypothetical and the participants are not required to pay for their choices.
Experimental Design Details
Not available
Randomization Method
The randomization will be done at the individual level by the survey company, stratifying by age, gender, and education.
Randomization Unit
Randomization unit is the “individual.”
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
150 individuals for the pre-test, 1,200 individuals for the main survey
Sample size: planned number of observations
150 individuals for the pre-test, 1,200 individuals for the main survey
Sample size (or number of clusters) by treatment arms
For the pretesting: 50 individuals for each of the three sub-samples; for the main survey: 400 individuals for each of the three sub-samples.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
I find that the MDEs are 0.18 pounds for the difference between samples 3 and 1, and between samples 3 and 2. Furthermore, the MDEs for the difference between samples 1 and 2 is 0.36 pounds. All differences correspond to 18% of the standard deviation. Please refer to Appendix B of the attached proposal in the section "Supporting Documents & Materials" for the details of the power calculation.
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
The Ethics Committee of University of St.Gallen
IRB Approval Date
2024-03-01
IRB Approval Number
Exempt (N/A)