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Comparing personal and general SMS reminders for gym attendance
Last registered on July 12, 2017

Pre-Trial

Trial Information
General Information
Title
Comparing personal and general SMS reminders for gym attendance
RCT ID
AEARCTR-0002144
Initial registration date
July 07, 2017
Last updated
July 12, 2017 9:32 PM EDT
Location(s)
Region
Primary Investigator
Affiliation
Harvard T. H. Chan School of Public Health
Other Primary Investigator(s)
Additional Trial Information
Status
Completed
Start date
2016-02-01
End date
2017-04-01
Secondary IDs
Abstract
Individuals often fail to exercise regularly. Time-inconsistent behavior occurs because physical activity incurs an immediate effort and delayed benefits. Economists have sought to exploit present-bias by providing members with financial incentives, but these programs are costly to run and their effect on attendance often fails to persist once payments stop. An alternative is to use low-cost SMS reminders to achieve behavior change. We ran a randomized controlled trial on members of 12 branches of a gym in Montreal (from Feb. 1st 2016) to compare generic reminders for gym attendance with reminders that recalled participants' own exercise goals. Subject were given the choice to participate in the study when signing up or renewing their gym memberships.
External Link(s)
Registration Citation
Citation
Moscoe, Ellen. 2017. "Comparing personal and general SMS reminders for gym attendance." AEA RCT Registry. July 12. https://doi.org/10.1257/rct.2144-1.0.
Former Citation
Moscoe, Ellen. 2017. "Comparing personal and general SMS reminders for gym attendance." AEA RCT Registry. July 12. http://www.socialscienceregistry.org/trials/2144/history/19373.
Experimental Details
Interventions
Intervention(s)
The intervention consists of sending SMS reminders to gym members every 15 days during the study period. Participants were randomized to 2 groups: general reminder and personal goal reminder. The general reminder simply reminded participants to go to the gym. The personal goal reminder included participant-specific exercise goals elicited at baseline and reminded them to go to the gym.
Intervention Start Date
2016-05-01
Intervention End Date
2017-03-01
Primary Outcomes
Primary Outcomes (end points)
Primary outcomes are: total gym visits in study period, average weekly gym visits, and probability of attaining one's exercise goal.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The study has a very simple 2-group stratified randomization design. Participants were randomized to 2 equal groups (N=360) (general or personal goal reminder) with stratification on key baseline variables (prior gym attendance and weekly attendance goal.)
Experimental Design Details
Randomization Method
Randomization was done on a computer using Stata 12.
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
None, done at the individual level
Sample size: planned number of observations
360
Sample size (or number of clusters) by treatment arms
180 in each reminder group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Universite du Quebec a Montreal
IRB Approval Date
2016-01-28
IRB Approval Number
839
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is 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