A large-scale RCT informing gasoline car owners on the private and social benefits of transitioning to electric vehicles

Last registered on October 05, 2022

Pre-Trial

Trial Information

General Information

Title
A large-scale RCT informing gasoline car owners on the private and social benefits of transitioning to electric vehicles
RCT ID
AEARCTR-0010162
Initial registration date
October 03, 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
October 05, 2022, 11:17 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
National University of Singapore

Other Primary Investigator(s)

PI Affiliation
National University of Singapore

Additional Trial Information

Status
In development
Start date
2022-10-05
End date
2024-04-01
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We are collaborating with a leading financial institution in Singapore to experiment with different ways of encouraging its account holders (clients) who regularly purchase gasoline to adopt electric vehicles (EV). The experiments involve four information treatments including a control group, whereby we provide up-to-date information in various forms. These include the private benefits of EV ownership, the social benefits of EV ownership, and salient information about financial incentives of EV adoption that the financial institution already provides to the general public. The information experiments will be implemented by the financial institution among 32,000 clients and is expected to last 14 weeks, from October 2022 to January 2023. Through our employer (National University of Singapore), we signed a Research Collaboration Agreement with the financial institution on August 17, 2022, which "regulates (our) collaboration in relation to the research project entitled 'EV (Energy Reset) Adoption'" and includes a detailed work plan and project schedule. The final milestone is to produce a research article that is published in a scientific journal.
External Link(s)

Registration Citation

Citation
Salvo, Alberto and Bing Yang Tan. 2022. "A large-scale RCT informing gasoline car owners on the private and social benefits of transitioning to electric vehicles." AEA RCT Registry. October 05. https://doi.org/10.1257/rct.10162-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
The experiments involve four information treatments including a control group, each group composed of 8000 clients of a leading financial institution, totaling 32,000 participants. The information to be shared with participants include the private benefits of EV ownership relative to gasoline vehicles (including charging infrastructure), the social benefits of EV ownership, and salient information about financial incentives of EV adoption that the financial institution already provides to the general public. Participants will be sent information at least once between October 2022 and January 2023 ["information campaign"], after which they will be surveyed on whether they purchased a vehicle in the past quarter ["endline survey"].
Intervention Start Date
2022-10-05
Intervention End Date
2023-01-06

Primary Outcomes

Primary Outcomes (end points)
Which type of car was purchased including none in the last 3 months (even if undelivered)
Primary Outcomes (explanation)
[All data are anonymized]

Participants, all of whom are clients of the FI, not only finance their car purchases through the FI but also through competing financial institutions and other firms such as car dealers and OEMs. Alternatively, some buyers purchase a car without a loan. For this reason, at the end of the information campaign we will survey all participants on their car purchases rather than rely on the FI's loan book.

We know that the endline survey response rate will be significantly below 100%. Importantly, we aim to achieve a similar survey response rate across the four treatment groups. If there are disparities in the survey response rate between groups, to compare participants accounting for similar proportions across the groups we may consider the earlier responses in those groups for which we obtain higher response rates.

The FI has a team responsible for surveying its clients. Based on their advice and pending the response rate in the days after launching the endline survey, we may consider incentivizing clients to increase the survey participation rate (e.g., with a voucher reward or a "lucky draw").

In addition to the endline survey results, we will also examine car purchases in the FI's loan book across the four treatment groups.

Secondary Outcomes

Secondary Outcomes (end points)
We will observe anonymous visits to the four information websites. A different website is accessible to each treatment group, to complement the email communications. These websites were prepared for the purpose of the experiment and were not publicized elsewhere. We will also observe interest in Emissions Reduction Certificates (see below).

We will also observe the anonymous participants' spending on gasoline and on public transport (sum across credit and debit cards issued by the FI we are working with) in the months after the information campaign. This complements the analysis of demographic information by anonymous participant, which includes spending on gasoline and public transport during a baseline pre-period, when choosing the experimental sample (see below).
Secondary Outcomes (explanation)
Participants in two of the treatment groups, should they transition to an EV, will be offered the opportunity to sign up to receiving an "Emissions Reduction Certificate (ERC) [which they] can share on social media [to] encourage others to make the switch. [The] ERC will include an updated carbon calculator figure."

Experimental Design

Experimental Design
The sample is composed of clients of the FI who have purchased car finance in the last decade (overwhelmingly for gasoline cars) and/or spent above a certain amount on gasoline in the past quarter. Participants will be randomized across the four information treatments.
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer. Prior to launching the experimental campaign we will confirm that demographic variables of subjects (age, gender, education, income, residential area, past car financing, past purchases of gasoline) are balanced across the treatment groups.
Randomization Unit
Individual randomization
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
32,000 individuals
Sample size: planned number of observations
32,000 individuals
Sample size (or number of clusters) by treatment arms
8000 individuals control, 8000 individuals for information on private benefits, 8000 individuals for information on private and social benefits, 8000 individuals for information on private and social benefits coupled with salient information on more attractive financing that the FI already provides to the general public.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Given a sample size of 32,000 (if all respond to the endline survey) and a base probability of buying a new car of 2.5% [1], we can detect an increase in probability of about 0.66 percentage points. This is about a 25% increase in the probability. [1] Based on an information campaign period of 3 months out of 120 months of Singapore's Certificate of Entitlement (a car license) eligibility.
IRB

Institutional Review Boards (IRBs)

IRB Name
NUS Department of Economics Departmental Ethics Review Committee (DERC)
IRB Approval Date
2022-07-25
IRB Approval Number
N/A