Study Stopped
This study was suspended due to low take-up in the group commitment contracts arm (\~6%), revealing inadequate statistical power to justify moving forward. There were no safety concerns.
The Impact of Group Commitment Contracts on Smoking Cessation and Weight Loss
1 other identifier
interventional
3,600
1 country
1
Brief Summary
We will conduct a randomized controlled trial to evaluate the effectiveness of group commitment contracts for smoking cessation and weight loss.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for not_applicable
Started Dec 2023
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
January 8, 2020
CompletedFirst Posted
Study publicly available on registry
January 13, 2020
CompletedStudy Start
First participant enrolled
December 18, 2023
CompletedPrimary Completion
Last participant's last visit for primary outcome
June 19, 2025
CompletedStudy Completion
Last participant's last visit for all outcomes
June 19, 2025
CompletedApril 16, 2024
April 1, 2024
1.5 years
January 8, 2020
April 13, 2024
Conditions
Outcome Measures
Primary Outcomes (1)
Smoking Cessation / Weight Loss
Participants will be directly prompted to answer whether they have been able to quit smoking or reach their target weight in the past six months. If a participant self-reports a claim of success, they will be asked to furnish at-home (and, in some cases, in-person) verification.
6 months
Other Outcomes (1)
Smoking Cessation / Weight Loss by Sex/Gender, Race, and Ethnicity
6 months
Study Arms (7)
Control
NO INTERVENTIONSubjects are not offered a group commitment contract, individual commitment contract, or individual monetary rewards. Subjects do not receive additional information treatments.
Group Commitment Contract + Information
EXPERIMENTALSubjects are offered a group commitment contract for smoking cessation or weight loss and receive additional information treatments.
Individual Monetary Rewards + Information
EXPERIMENTALSubjects are offered individual monetary rewards for smoking cessation or weight loss and receive additional information treatments.
Individual Commitment Contract + Information
EXPERIMENTALSubjects are offered an individual commitment contract for smoking cessation or weight loss and receive additional information treatments.
Group Commitment Contract
EXPERIMENTALSubjects are offered a group commitment contract for smoking cessation or weight loss and receive no additional information treatments.
Individual Monetary Rewards
EXPERIMENTALSubjects are offered individual monetary rewards for smoking cessation or weight loss and receive no additional information treatments.
Individual Commitment Contract
EXPERIMENTALSubjects are offered an individual commitment contract for smoking cessation or weight loss and receive no additional information treatments.
Interventions
A group contract where the primary individual, who will be tracked by the study, can invite peers to join the contract and form their group. To initiate a contract, a user must choose: the stakes, start date, and (for weight loss contracts) target weight, and and, optionally, to allow other members to have the power to invite other people to join the group.
Individuals eligible for a $100 monetary reward (incentive) following verified smoking cessation or weight loss.
Individuals will have the opportunity to create an individual commitment contract to quit smoking. They will have the option to set the stakes, start date, and (for weight loss contracts) target weight.
In the initial survey, participants will receive additional information treatments on the likelihood of success of the different incentives and contracts, with the goal of shifting "naives" to "sophisticates."
Eligibility Criteria
You may qualify if:
- Aged 18 years or older
- Has smartphone with capability to reach internet daily and download app
- Able and willing to visit Quest location or take an at-home verification test
- Willing to furnish a payment method for commitment contract stakes
- If completing a smoking cessation contract:
- Daily smoker
- If completing a weight loss contract:
- Has access to a functioning scale
- Interest in losing weight at a pace of 2 lb or fewer per week, with a target BMI at or above 18.5
You may not qualify if:
- Pregnancy
- Any terminal illness
Contact the study team to confirm eligibility.
Sponsors & Collaborators
Study Sites (1)
Northwestern University, Global Poverty Research Lab
Evanston, Illinois, 60208, United States
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Dean Karlan, PhD
Northwestern University
- PRINCIPAL INVESTIGATOR
Anna Tuchman, PhD
Northwestern University
- PRINCIPAL INVESTIGATOR
Jonathan Zinman, PhD
Dartmouth College
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- NONE
- Purpose
- PREVENTION
- Intervention Model
- PARALLEL
- Sponsor Type
- OTHER
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
January 8, 2020
First Posted
January 13, 2020
Study Start
December 18, 2023
Primary Completion
June 19, 2025
Study Completion
June 19, 2025
Last Updated
April 16, 2024
Record last verified: 2024-04
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE