From car ownership to carsharing: the effect of tailored information and framing

Last registered on October 05, 2021

Pre-Trial

Trial Information

General Information

Title
From car ownership to carsharing: the effect of tailored information and framing
RCT ID
AEARCTR-0008100
Initial registration date
October 04, 2021
Last updated
October 05, 2021, 2:50 PM EDT

Locations

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Primary Investigator

Affiliation
Institute of Transport Economics

Other Primary Investigator(s)

Additional Trial Information

Status
In development
Start date
2021-08-15
End date
2022-07-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
As a sustainable transition, carsharing can be beneficial along each of the sustainability dimensions: the environmental, the economic, the social. Carsharing: a service to hire a car on a per-hour/day basis, may imply less car use, reducing emissions and the number cars on the roads compared to private car ownership. Carsharing is more rational and efficient: fewer cars and lower fixed costs, and it provides an easy and affordable access to car for those who only need it occasionally or cannot afford to buy a car.
Recent results from the literature highlighted a general lack of information around car-sharing in Norway. How to inform people, and what kind of information can impact individual choice and facilitate diffusion of this innovative transport mode, have, as far as we know, not been addressed in the literature.
The goal of the trial is to increase carsharing, ideally by people who have an old and underutilized car and might be persuaded to go car-less, or who are considering to purchase a (second) car. This will be achieved by running a large-scale randomized controlled trial in the field, where a selected targeted audience, based on their predicted receptiveness to car-sharing, will be nudged over to car-sharing by using a car-sharing calculator.
External Link(s)

Registration Citation

Citation
Ciccone, Alice. 2021. "From car ownership to carsharing: the effect of tailored information and framing." AEA RCT Registry. October 05. https://doi.org/10.1257/rct.8100-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
The goal of the trial is to motivate people to shift from car ownership to carsharing. We will try to achieve this goal by nudging people to carsharing. Through a large-scale randomized controlled trial in the field, we will send tailored information about potential gain of switching to carsharing to people who have a car but might be persuaded to go car-less, or who might purchased a (second) car.
Intervention Start Date
2021-10-30
Intervention End Date
2022-02-28

Primary Outcomes

Primary Outcomes (end points)
Number of active carsharing members per postcode before and after being exposed to treatment compared to control areas.
Primary Outcomes (explanation)
For 3 carsharing companies: a new active carsharing member = 1 if they either enroll (pay the membership fee), or rent a car for the first time after (few months) the start of the trial.

This outcome variable will be measured directly through the carsharing data (before/after+treatment/control)

Secondary Outcomes

Secondary Outcomes (end points)
Click through rate to carsharing companies website (proxy to willingness to start carsharing).
Secondary Outcomes (explanation)
We will compare two framing of the website: one with potential saving from switching to carsharing (gain) the other with potential loss of keeping the own car.

Experimental Design

Experimental Design
Two-arm design – a treatment group will receive encouragement to visit the website calculator, and a control group will not.
Experimental Design Details
Not available
Randomization Method
First outcome variable: randomization at the postcode level stratified by the existing level of carsharing (number of members for two companies)
Target audience: Owners of a diesel or gasoline car which is older than 6 y.o.
Exclusion criteria: People who live in postcodes without any existing car-sharing member (no service available) and are far away from the city (forest areas).

Randomization Unit
First outcome variable: Postcode level randomization.

Second outcome variable: individual level randomization
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
total of about 400 postcodes
Sample size: planned number of observations
about 200 (treated)
Sample size (or number of clusters) by treatment arms
about 200 postcodes treated and 200 as control.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Using standard values for alpha=0.05 and beta 0.8. We calculate that the size of the difference in the first outcome variable in the in the treatment vs. control group that the evaluation would be powered to detect (i.e. the number of additional car-sharing users as a result of the intervention) an increase of 15 car-sharing users per postcode (or a 27.7% increase). for the second outcome variable we estimate that the evaluation would be powered to detect an increase (or decrease) of 8 percentage points in the proportion of recipients of the email with link to the website with loss framing ("treatment B") who click-through to a car-sharing website, relative to receving an email with link to the website with gain framing ("treatment A").
IRB

Institutional Review Boards (IRBs)

IRB Name
The Norwegian Research Council
IRB Approval Date
2020-01-01
IRB Approval Number
300625
Analysis Plan

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