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The Impact of Group Commitment Contracts on Smoking Cessation and Weight Loss

The Impact of Group Commitment Contracts on Smoking Cessation and Weight Loss

Status
Suspended
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04224727
Enrollment
3600
Registered
2020-01-13
Start date
2023-12-18
Completion date
2025-06-19
Last updated
2024-04-16

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Smoking Cessation, Weight Loss

Brief summary

We will conduct a randomized controlled trial to evaluate the effectiveness of group commitment contracts for smoking cessation and weight loss.

Detailed description

Initial screening will be conducted online via the Qualtrics survey platform. Respondents meeting the inclusion/exclusion criteria will immediately be randomized into one of the intervention arms described below, and then take a baseline survey. This baseline survey will also be conducted online via the Qualtrics survey platform. The initial screening, randomization, and baseline survey should take approximately 15 minutes total and can be completed anywhere the participant has an internet connection. INTERVENTION: Respondents who meet the inclusion/exclusion criteria will be randomized into one of the following arms: 1. Control Arm (No Intervention) 2. Group Contract Arm 3. Individual Monetary Rewards Arm 4. Individual Commitment Contract Arm Subjects in Arms #2-4 will be cross-randomized into two subgroups: A. Additional information treatments on the likelihood of success of the different incentives and contracts, with the goal of shifting naives to sophisticates. B. No additional information treatments. FOLLOW-UP SURVEY: After the participants finish their contract, they will be emailed a link to the follow-up survey that will be administered online via the Qualtrics survey platform. The survey should take approximately 5 minutes and can be completed anywhere the participant has an internet connection. Participants will be directly prompted to answer whether they have been able to quit smoking or lose their target weight in the past six months. If a participant self-reports a claim of smoking cessation or successful weight loss, they will be asked to furnish at-home verification of their claim. IN-PERSON VERIFICATION: A randomly selected subset of successful participants will be asked for in-person verification of their claim with a urine test (smoking cessation) or in-person weigh-in (weight loss) at a Quest Diagnostics location of their choice.

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.

BEHAVIORALIndividual Monetary Rewards

Individuals eligible for a $100 monetary reward (incentive) following verified smoking cessation or weight loss.

BEHAVIORALIndividual Commitment Contract

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.

OTHERInformation

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.

Sponsors

Northwestern University
CollaboratorOTHER
National Bureau of Economic Research, Inc.
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE

Intervention model description

Respondents who meet the inclusion/exclusion criteria will be randomized into one of the following arms: 1. Control Arm (No Intervention) 2. Group Contract Arm 3. Individual Monetary Rewards Arm 4. Individual Commitment Contract Arm To understand the effect that knowledge about the effectiveness of commitment contracts has on uptake, smoking quit rates, and weight loss, we will be cross-randomizing those assigned to Arms #2-4 into further subgroups: Subgroup A. 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. In other words, we aim to provide information that will encourage present-biased or loss-averse individuals to participate in the programs that offer the greatest chance at success. Subgroup B. Participants will not receive any information about commitment contracts.

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes

Inclusion criteria

* 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

Exclusion criteria

* Pregnancy * Any terminal illness

Design outcomes

Primary

MeasureTime frameDescription
Smoking Cessation / Weight Loss6 monthsParticipants 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.

Other

MeasureTime frameDescription
Smoking Cessation / Weight Loss by Sex/Gender, Race, and Ethnicity6 monthsParticipants 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.

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026