Social Influence and Mitigation

Last registered on January 23, 2023

View Trial History

Pre-Trial

Trial Information

General Information

Title

Social Influence and Mitigation

RCT ID

AEARCTR-0010768

Initial registration date

January 13, 2023

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

January 23, 2023, 8:05 AM EST

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

Locations

Country

United Kingdom of Great Britain and Northern Ireland

Region

all

Primary Investigator

Name

Friederike Mengel

Affiliation

Uni Essex

Contact Primary Investigator

Other Primary Investigator(s)

Additional Trial Information

Status

In development

Start date

2023-01-13

End date

2023-11-16

Keywords

Behavior, Environment & Energy

Additional Keywords

Climate Action; Social Influence

JEL code(s)

C92, D91, Q0

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

Many people feel powerless to do reduce climate change as the individual choices they can make are likely to only have negligible impact. If their choices were to influence many others, however, then collectively the impact would become more important. We will study how people’s decision to mitigate their climate impact depends on the possibility to have social influence. In a baseline treatment participants decide by how much to mitigate their climate impact by donating to a tree planting scheme. Additional treatments then allow for their decision to be observed by a number of others either before or after they make their choice. When others observe a decision before they make their choice this creates the possibility of social influence in the experiment.

External Link(s)

Registration Citation

Citation

Mengel, Friederike. 2023. "Social Influence and Mitigation." AEA RCT Registry. January 23. https://doi.org/10.1257/rct.10768-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

Intervention Start Date

2023-01-13

Intervention End Date

2023-04-13

Primary Outcomes

Primary Outcomes (end points)

Willingness to Mitigate (WTM)

Primary Outcomes (explanation)

We measure the willingness to mitigate by the amount of money participants are willing to give up to offset their carbon footprint.

Secondary Outcomes

Secondary Outcomes (end points)

Secondary Outcomes (explanation)

Experimental Design

We will study how people’s decision to mitigate their climate impact depends on the possibility to have social influence. In a baseline treatment participants decide by how much to mitigate their climate impact by donating to a tree planting scheme. Additional treatments then allow for their decision to be observed by a number of others either before or after they make their choice. When others observe a decision before they make their choice this creates the possibility of social influence in the experiment.

Experimental Design Details

We will conduct an online experiment consisting of two waves.

In Wave 1 there will be different treatments:
(i) a baseline, where participants are simply asked to choose how much of a 10 GBP endowment that they will be given to use to offset carbon. In addition we will ask them some demographic information and some views on climate issues.
(ii) several influence and observability conditions where participants are told that their choice will anonymously be shown to a number of Wave 2 participants.

Influence conditions will differ by the amount of people each Wave 1 participant is observed by and the amount of people that each Wave 2 participant observes.

In Wave 2 participants make the same choice as in Wave 1 but this time they will see additional information of the sort “A randomly drawn participant from a previous wave of this survey decided to use 4.70 GBP for mitigation” (where the actual numbers used will be from the actual Wave 1 choices). They will either see this type of information before or after making their choice allowing us to distinguish the effect of influence from observability.
The money participants decide to use to mitigate will be donated to the tree planting scheme at mycarbonplan.org

Randomization Method

online platform

Randomization Unit

individual

Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters

n/a

Sample size: planned number of observations

1860 participants in Wave 1 and 3384 participants in Wave 2

Sample size (or number of clusters) by treatment arms

In Wave 1 we plan to have 240 participants per treatment except for the conditions where each individual is uniquely observed by twenty others in Wave 2. For those conditions we plan on 60 participants in Wave 1. The reason is that otherwise Wave 2 sample sizes would become extremely large. (240 Wave 1 participants in this condition would correspond to 4800 Wave 2 participants for this condition alone). We will have 300 participants (240+60) in the baseline treatment (without influence/observability).

In sum we will have the following sample sizes for our Wave 1 treatments:

Baseline: 300; Influence 1-1: 240; Influence 1-20: 60; Influence 20-1: 240; Influence 20-20: 240
Observability 1-1: 240; Observability 1-20: 60; Observability 20-1: 240; Observability 20-20: 240, where Influence x-y denotes an influence treatment where each Wave 1 participant is observed by x others who each observe y others in total.

Sample sizes in Wave 2 then directly follow from these.

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Power analysis based on t-tests comparing two independent means shows that these sample sizes allow us to detect an effect in terms of a treatment difference between WTM between baseline and Influence 1-1 or Influence 1-1 and Observability 1-1 of about 0.24-0.25 GBP at the 5% level with 80% power.

Supporting Documents and Materials

IRB