Encouraging active transport: an RCT on mobile devices

Last registered on June 18, 2022


Trial Information

General Information

Encouraging active transport: an RCT on mobile devices
Initial registration date
June 17, 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
June 18, 2022, 10:26 AM EDT

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



Primary Investigator

VATT Institute for Economic Research

Other Primary Investigator(s)

PI Affiliation
University of Helsinki

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
The goal of the research project is to evaluate the effectiveness of health messages in encouraging active modes of transport. Active transport refers to walking and cycling, either as the sole mode of transport or as part of trips done via public transport. The intervention will be carried out using a mobile application with an algorithm that automatically tracks mobility and transport mode, including walking, cycling, car, bus, tram and train. The application is currently used to inform individuals of the carbon footprint of their daily transport. During the intervention, half of the application users will be randomized into a treatment group which will receive information on their level of active transport and on the health impacts in the form of reduced risk for certain health conditions.
External Link(s)

Registration Citation

Ahlvik, Lassi and Anna Sahari. 2022. "Encouraging active transport: an RCT on mobile devices." AEA RCT Registry. June 18. https://doi.org/10.1257/rct.9600
Experimental Details


The intervention makes use of a mobile application which automatically tracks the daily mobility of users who have chosen to install the application. The application informs its users of the carbon footprint of their daily transport and it is provided by the City of Tampere for residents and visitors in the region. During the intervention, half of the application users will be randomized into a treatment group which will receive additional information on their level of their active transport (walking and cycling) and its health impacts.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Amount of walking (length, time) and amount of cycling (length, time)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Amount of driving and use of public transport (length and time by mode), carbon footprint of transport
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Half of the users of the application will be randomized into a treatment group. This group will receive an update to their application, which will give the following information using visuals and messages: their level of active transport on a daily and weekly level, historical data on their activity level, comparison to other application users and the impact of weekly activity on health risks. The intervention will last three months.
Experimental Design Details
Not available
Randomization Method
Randomization by computer
Randomization Unit
Individual-level randomization by strata. For the randomization, we will create strata based on pre-treatment level of walking (high/low), pre-treatment level of cycling (high/low) and location by postal code. This is to ensure geograhical coverage and observations from all levels of pre-treatment activity.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
2000 individuals
Sample size: planned number of observations
2000 individuals
Sample size (or number of clusters) by treatment arms
1000 individuals in control, 1000 individuals in treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Walking: 40 meter change (2.3%) Cycling: 60 meter change (7.8%)

Institutional Review Boards (IRBs)

IRB Name
University of Helsinki Ethical Review Board in Humanities and Social and Behavioral Sciences
IRB Approval Date
IRB Approval Number
Analysis Plan

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