Behavioral Strategies for Local Government: Encouraging Australian Capital Territory Citizens to Update Contact Details

Last registered on August 22, 2025
View Trial History

Pre-Trial

Trial Information

General Information

Title
Behavioral Strategies for Local Government: Encouraging Australian Capital Territory Citizens to Update Contact Details
RCT ID
AEARCTR-0016602
Initial registration date
August 22, 2025

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
August 22, 2025, 6:16 AM EDT

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

Locations

Country
Australia
Region
Australian Capital Territory

Primary Investigator

Name
Mathias Sinning
Affiliation
Australian National University
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Ralf Steinhauser
PI Affiliation
Australian National University
Contact Investigator

Additional Trial Information

Status
Completed
Start date
2025-05-23
End date
2025-08-01
Keywords
Behavior, Environment & Energy, Governance
Additional Keywords
Local Government Administration; Provision of Public Services
JEL code(s)
C93, H83
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This study tests different ways of encouraging Canberra residents to keep their contact details up to date and to sign up for electronic communication with local government. Individuals who hold a driver licence or have a registered vehicle in the Australian Capital Territory were randomly placed into one of four groups. Three of the groups received a different type of letter in the mail, and one group did not receive a letter. Letter 1 reminded citizens of the legal requirement to update their address within 14 days if it changes. Letter 2 gives the same reminder and also explains the possible extra costs if fines are not received or paid on time. Letter 3 gives the same reminder and also encourages citizens to choose electronic communication to help the environment. Around 1,200 citizens received each type of letter. The aim of the trial is to show which approach is most effective in motivating citizens to update their contact details and choose electronic communication.
External Link(s)

Registration Citation

Citation
Sinning, Mathias and Ralf Steinhauser. 2025. "Behavioral Strategies for Local Government: Encouraging Australian Capital Territory Citizens to Update Contact Details." AEA RCT Registry. August 22. https://doi.org/10.1257/rct.16602-1.0
Sponsors & Partners

Sponsors

Partner

Name
Australian Capital Territory Government, Chief Minister, Treasury and Economic Development Directorate
Type
municipality
URL
https://www.cmtedd.act.gov.au
Experimental Details

Interventions

Intervention(s)
This study tested different letter messages designed to encourage residents of the Australian Capital Territory (ACT) to update their contact details and sign up for electronic communication with the ACT Government. Vehicle registration and driver licence holders who had not opted in to electronic communication were randomly assigned to one of three treatment groups or a control group.

Letter 1 (neutral reminder): emphasized the legal requirement to notify address changes within 14 days.
Letter 2 (cost message): repeated the reminder and highlighted possible extra fees if fines are not received or paid.
Letter 3 (environmental message): repeated the reminder and promoted the environmental benefits of switching to paperless communication.

Outcomes from administrative records will measure whether participants updated their contact details (e.g., phone, email, address) or signed up for electronic communication after receiving the letters.
Intervention (Hidden)
Intervention Start Date
2025-05-23
Intervention End Date
2025-08-01

Primary Outcomes

Primary Outcomes (end points)
The key outcomes of interest are whether, after receiving the intervention letters, participants:
1. Update their contact details in the Access Canberra system, including:
- Adding or changing a mobile phone number
- Adding or changing a work phone number
- Adding, updating, or removing an email address
- Updating postal or residential address
2. Sign up for electronic communication, measured by:
- Opting in to SMS notifications
- Opting in to email notifications (where identifiable in the system)
Outcomes will be measured using administrative records, with the date of first change recorded after the mailout.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This is a randomised controlled trial testing different letter messages to encourage residents of the Australian Capital Territory (ACT) to update their contact details and to sign up for electronic communication with the ACT Government. Eligible vehicle registration and driver licence holders who had not yet opted in to electronic communication were randomly assigned to one of three treatment groups or a control group. Each treatment group received a different version of a mailed letter: a neutral reminder, a reminder highlighting potential costs of non-compliance, or a reminder emphasising environmental benefits of electronic communication. The control group received no letter during the trial period. Outcomes will be measured using administrative records to assess whether participants updated their contact details or signed up for electronic communication after the intervention.
Experimental Design Details
Randomization Method
Participants were randomly assigned to treatment and control groups by computer. Randomization was stratified to ensure balance across key demographic and geographic characteristics recorded in the Access Canberra registration system. The stratification variables included:
- Age group (34 or under; 35–49; 50–64; 65+; Organization clients)
- Gender (Female; Male; Organization clients)
- Suburb (standardized list of ACT suburbs; non-ACT addresses grouped into “NSW” or “Other State”; small-count suburbs grouped into “Other ACT Suburb”)
- District (derived from suburb; NA for interstate and “Other ACT Suburb” groups)
- Postcode (derived from suburb, to correct for postcode errors in administrative records; NA for interstate and “Other ACT Suburb” groups)
Randomization assigned individuals to one of three treatment groups (each receiving a different type of letter) or to a control group that did not receive a letter during the trial period. To reduce re-identification risk while maintaining statistical power, a 20% sample of the control group was retained for analysis.
Randomization Unit
The unit of randomization is the individual client record in the Access Canberra vehicle registration and driver licensing system. Stratified randomization was used to ensure balance across strata defined by age group, gender, and suburb (with suburb further grouped into districts, postcodes, and broader categories such as “NSW,” “Other State,” and “Other ACT Suburb”). Each eligible individual was randomly assigned within these strata to one of three treatment groups or to the control group.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
32,425 individual clients (the unit of randomization) in the Access Canberra registration system.
Sample size: planned number of observations
32,425 individuals.
Sample size (or number of clusters) by treatment arms
Control group (20% sample): 28,826 individuals
Treatment group 1: 1,196 individuals
Treatment group 2: 1,207 individuals
Treatment group 3: 1,196 individuals
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Human Ethics Office, Australian National University
IRB Approval Date
2025-08-21
IRB Approval Number
H/2025/0510
Analysis Plan

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Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
August 01, 2025, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
August 01, 2025, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
Control=28,826 individuals; Treatment 1=1,196 individuals; Treatment 2=1,207 individuals; Treatment 3=1,196 individuals. Total=32,425 individuals.
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
Control=28,826 individuals; Treatment 1=1,196 individuals; Treatment 2=1,207 individuals; Treatment 3=1,196 individuals. Total=32,425 individuals.
Final Sample Size (or Number of Clusters) by Treatment Arms
Control=28,826 individuals; Treatment 1=1,196 individuals; Treatment 2=1,207 individuals; Treatment 3=1,196 individuals. Total=32,425 individuals.
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
No
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials