Nudge Driving Safety: Evidence from a Field Experiment

Last registered on July 28, 2022

Pre-Trial

Trial Information

General Information

Title
Nudge Driving Safety: Evidence from a Field Experiment
RCT ID
AEARCTR-0009769
Initial registration date
July 27, 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
July 28, 2022, 3:03 PM EDT

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

Locations

Region

Primary Investigator

Affiliation
Zhejiang University

Other Primary Investigator(s)

PI Affiliation

Additional Trial Information

Status
On going
Start date
2022-04-01
End date
2022-08-28
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
With the rise of the sharing economy, more and more drivers have joined online car-hailing platforms. On the one hand, this has brought new benefits to the platform. On the other hand, risky driving habits also bring a lot of safety hazards to platforms and society. Therefore, how to nudge drivers to develop good driving habits has become an urgent problem.
In this study, we plan to conduct a large-scale field experiment in China. We will select drivers with similar historical performance on an online car-hailing platform and randomly assign them to a course learning group, a voice broadcast group, a positive framing group, a negative framing group, a money incentive group, an honorary incentive group, team competition groups, and control groups. In the one-month experiment, by obtaining the GPS positioning information of the driver's mobile phone, we would take the zebra crossing overspeed ratio as the main indicator of the driver's driving behavior, and continue to observe the driver's driving behavior for another two weeks after the end of the experiment.
After the experiment, we expect to get the following results: (1) Compared with the control group, the zebra crossing overspeed ratio of the intervention group is lower; (2) Compared with the course learning group, the zebra crossing overspeed ratio of voice broadcast group is lower; (3) Compared with individual drivers participating in the safe driving competition, the zebra crossing overspeed ratio of drivers in teams is lower; (4) Compared with the positive framing group, the zebra crossing overspeed ratio of the negative framing group is lower; (5) Compared with the honorary incentive group, the zebra crossing overspeed ratio of the money incentive group is lower.
External Link(s)

Registration Citation

Citation
Chen, Fadong and Jiatong Han. 2022. "Nudge Driving Safety: Evidence from a Field Experiment." AEA RCT Registry. July 28. https://doi.org/10.1257/rct.9769
Experimental Details

Interventions

Intervention(s)
Different groups have different interventions.
Control group: no intervention.
Course learning group: drivers need to learn safe driving courses and pass the exam before starting their work at the beginning of each week, 4 times in total.
Voice broadcast group: drivers will receive a voice broadcast before starting their work at the beginning of each week, 4 times in total.
Positive framing effect group: the staff will communicate with the drivers by telephone to emphasize the positive effect of safe driving, once every two weeks, twice in total.
Negative framing effect group: the staff will communicate with the drivers by telephone to emphasize the negative effect of risky driving, once every two weeks, twice in total.
Money incentive group: drivers will participate in the safe driving competition alone, and drivers who perform well will be rewarded with money. Drivers will be rewarded at the end of the second week, the third week, and the fourth week respectively.
Honorary incentive group: drivers will participate in the safe driving competition alone, and drivers who perform well will be rewarded with banners which can be decorated on the car. Drivers will be rewarded at the end of the second week, the third week, and the fourth week respectively.
Team competition group: drivers will participate in the safe driving competition in teams, and teams who perform well will be rewarded with money. Drivers will be rewarded at the end of the second week, the third week, and the fourth week respectively.
Team competition control group: drivers are in teams but have no intervention.
Intervention Start Date
2022-07-18
Intervention End Date
2022-08-14

Primary Outcomes

Primary Outcomes (end points)
Drivers' zebra crossing overspeed ratio in different groups.
Primary Outcomes (explanation)
Zebra crossing overspeed ratio: times of speeding at zebra crossings / number of crossing zebra crossings.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The purpose of the study is to find out the best way to nudge drivers to drive safely.
We plan to select drivers who worked 100-250 hours in the past month and had zebra crossing speeding behavior in the past three months. Then we would assign them to groups randomly by a computer. Due to the limitation of the total number of drivers, the experiment will be conducted in two cities A and B.
In city A, there would be one control group (200 drivers), one course learning group (200 drivers), one voice broadcast group (200 drivers), one positive framing group (200 drivers), one negative framing group (200 drivers), one money incentive group (200 drivers).In city B, there would be one control group (200 drivers), one honorary incentive group (200 drivers), one team competition group (20 teams, 400 drivers), and one team competition control group (20 teams, 400 drivers).
Details of the experimental intervention are described above. We are mainly interested in the zebra crossing overspeed ratio of drivers. The experiment would continue for four weeks and observe the driver's driving behavior for another two weeks after the experiment.
Experimental Design Details
Randomization Method
Randomization done in office by a computer.
Randomization Unit
We plan to select drivers who worked 100-250 hours in the past month and had zebra crossing speeding behavior in the past three months. Then we would randomly assign them to groups.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
Ten groups and every group have about 200 drivers except for two competition groups which have 20 teams (each team has around 20 drivers) respectively. The observation is the number of times of speeding at zebra crossings per driver.
Sample size: planned number of observations
Ten groups and every group have about 200 drivers except for two competition groups which have 20 teams (each team has around 20 drivers) respectively. The observation is the number of times of speeding at zebra crossings per driver.
Sample size (or number of clusters) by treatment arms
Two control groups (each has 200 drivers), one course learning group (200 drivers), one voice broadcast group (200 drivers), one positive framing group (200 drivers), one negative framing group (200 drivers), one money incentive group (200 drivers), one honorary incentive group (200 drivers), one team competition group (20 teams, 400 drivers), one team competition control group (20 teams, 400 drivers).
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Two tails t test Effect size = 0.3, alpha = 0.05, power = 0.95, Df = 146, total sample size = 147, actual power = 0.95. Difference-in-Differences Linear Regressions Effect size = 0.15, alpha = 0.05, power = 0.95, number of predictors = 3, total sample size = 119, actual power = 0.95. Calculated by G*Power.
IRB

Institutional Review Boards (IRBs)

IRB Name
Neuromanagement Lab Institutional Review Board, Zhejiang University
IRB Approval Date
2022-04-01
IRB Approval Number
N/A

Post-Trial

Post Trial Information

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials