GHG emission abatement around the zero reference point

Last registered on October 07, 2026

Pre-Trial

Trial Information

General Information

Title
GHG emission abatement around the zero reference point
RCT ID
AEARCTR-0019497
Initial registration date
October 06, 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
October 07, 2026, 11:15 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

Affiliation
Universität Mannheim

Other Primary Investigator(s)

PI Affiliation
University of Wisconsin - Madison
PI Affiliation
Independent

Additional Trial Information

Status
In development
Start date
2026-10-05
End date
2026-10-30
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
Economies around the world are increasingly setting zero-threshold emissions targets. To achieve zero-threshold emissions, market mechanisms, such as emission trading systems, encourage emission reductions where they are the most cost-efficient. We investigate whether salient sustainability achievements around reference points, such as zero-threshold emissions, serve as heuristic cues for retail investors making investment decisions in such market environments. Based on theory on heuristic decision-making, we predict that retail investors are more likely to invest in a bond disclosing emissions achieving the zero-reference point, even when the emission abatement behind this achievement is more costly than the current market price for abatement. We aim to collect process evidence for reference points reducing decision-making effort by combining different reference points with a separate versus joint evaluation of investment alternatives. We use evidence from previous experiments to calibrate power calculations and exclude possibly confounding decision elements.
External Link(s)

Registration Citation

Citation
Friedrich, Christian, Marco Meier and Christian Peters. 2026. "GHG emission abatement around the zero reference point." AEA RCT Registry. October 07. https://doi.org/10.1257/rct.19497-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
We use a full-factorial design and present participants with one of four experimental variants based on varying two manipulations:
Manipulation 1: Reference point: the reference point of the lower-emission bond can either be (i) zero-threshold or (ii) positive-residual emissions.
Manipulation 2: Evaluation type: We design the evaluation of information to be either a (i) separate or (ii) joint evaluation of the investment options.

Details can be found in the supporting document.
Intervention Start Date
2026-10-05
Intervention End Date
2026-10-30

Primary Outcomes

Primary Outcomes (end points)
Our key outcome variable is the investment decision participants make, which we measure as (i) the average reponse, on a scale from 0-100, to three items eliciting participants' willingness to invest in Bond A (see supporting document for the items) and (ii) money allocated to Bond A in an allocation task.

Details can be found in the supporting document.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
(1) The average response, on a scale from 0-100, to three items eliciting participants' willingness to invest in Bond A MINUS the average response, on a scale from 0-100, to three items eliciting participants' willingness to invest in Bond B.
(2) A dummy variable for whether the participant allocated any money to Bond A.
(3) The average response, on a scale from 0-100, to three items eliciting participants' willingness to invest in removal offsets
(4) The money allocated to removal offsets in an allocation task
(5) The share of a participant's available return allocated to removal offsets in an allocation task
(6) A dummy variable for whether the participant allocated any money to removal offsets.
(7) issuer-channel abatement = 1.5 x (allocation to A / 10,000 GBP)
(8) market-based abatement = allocation to offset / 120 GBP
(9) financial opportunity cost for each abatement channel
(10) reference-point focality index calculated as the average of two reference-point items (see supporting document)
(11) integrated-comparison index calculated as the average of two comparison items (see supporting document)
(12) time spent on willingness to invest assessments
(13) time spent on allocation task
(14) allocation revisions
(15) human-coded (based on blinded coding by several human coders) of whether written justification for decisions mentioned
• net zero / the zero reference point
• the return difference
• explicit A vs. B comparison
• opportunity cost
• offsets / 120 GBP per ton
• using the extra return from B to offset emissions
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We share a link to our online survey, which is fully presented in the supporting document, via Prolific. Participants are paid a flat participation fee according to Prolific policy of 2.5 GBP. Participants who click on the link are randomly assigned one of our treatments and fill in the survey on their personal device. We run the study, and randomization, on OTree.
Experimental Design Details
Not available
Randomization Method
Randomization is done by a computer through the OTree software.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
600 individuals
Sample size: planned number of observations
600 individuals
Sample size (or number of clusters) by treatment arms
approximately 150 individuals
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
All minimum detectable effect sizes are based on a 5% significance level and an 80% power level. We plan to conduct full-factorial ANOVAs with numerator degrees of freedom of 1 for all tests (main effects and interactions) and four groups (2 x 2 full-factorial analysis). We also plan to run a planned contrast test, which we analyze as a one-way ANOVA with a two-level factor. We express minimum detectable effect sizes as Cohen's f. Based on calculations with G*Power 3.1.9.7, our minimum detectable effect size is 0.1146 for all mentioned analyses. We have some data from previous experiments to gauge expectations of effect sizes. The previous experiment explored a similar reference point manipulation, but may have introduced design features that exaggerated effect sizes, which is why we expect somewhat smaller realized effect sizes. The observed effect size was 0.1515 (F = 7.34, df1,2 = [1, 320]). Moreover, the experiment also had an accompanying manipulation for the planned contrast test, but we expect our manipulation to be more subtle, which is why we expect much smaller realized effect sizes. The observed effect size was 0.1686 (F = 9.15, df1,2 = [1, 322]).
Supporting Documents and Materials

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IRB

Institutional Review Boards (IRBs)

IRB Name
University of Wisconsin-Madison Minimal Risk Research IRB
IRB Approval Date
2026-08-28
IRB Approval Number
2026-0939
IRB Name
University of Mannheim Ethics Committee
IRB Approval Date
2026-09-18
IRB Approval Number
47/2024
Analysis Plan

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