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Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation
Last registered on July 26, 2016

Pre-Trial

Trial Information
General Information
Title
Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation
RCT ID
AEARCTR-0001129
Initial registration date
July 26, 2016
Last updated
July 26, 2016 2:34 PM EDT
Location(s)
Primary Investigator
Affiliation
Northwestern University
Other Primary Investigator(s)
PI Affiliation
Development Economics Research Group, The World Bank
Additional Trial Information
Status
Completed
Start date
2006-08-01
End date
2008-05-31
Secondary IDs
Abstract
We designed and tested a voluntary commitment product to help smokers quit smoking. The product (CARES) offered smokers a savings account in which they deposit funds for six months, after which they take a urine test for nicotine and cotinine. If they pass, their money is returned; otherwise, their money is forfeited to charity. Of smokers offered CARES, 11 percent took up, and smokers randomly offered CARES were 3 percentage points more likely to pass the 6-month test than the control group. More importantly, this effect persisted in surprise tests at 12 months, indicating that CARES produced lasting smoking cessation.
External Link(s)
Registration Citation
Citation
Giné, Xavier and Dean Karlan. 2016. "Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation." AEA RCT Registry. July 26. https://doi.org/10.1257/rct.1129-1.0.
Former Citation
Giné, Xavier and Dean Karlan. 2016. "Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation." AEA RCT Registry. July 26. https://www.socialscienceregistry.org/trials/1129/history/9603.
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Experimental Details
Interventions
Intervention(s)
The Green Bank of Caraga identified regular smokers off the street and asked them if they wanted to participate in a short survey on smoking. All subjects received an informational pamphlet on the dangers of smoking, and a tip sheet on how to quit. After completing this baseline survey, subjects were randomly assigned to one of three conditions: the Committed Action to Reduce and End Smoking (CARES) product, cue cards, or neither (control).

CARES intervention: A minimum balance of 50 pesos (about US$1) was required to open a CARES account, where sample smokers were encouraged to deposit the money they would normally spend on cigarettes each week. Clients could deposit but not withdraw from these accounts, and the accounts yielded no interest, to discourage non-smokers people from using them as a substitute for normal savings accounts. A portion of the group also received weekly visits from deposit collectors, saving them the weekly trip to the bank while another portion didn’t.

Cue cards: These individuals got to choose from among four wallet-sized cards depicting negative health consequences of smoking: premature babies, bad teeth, black lung, or a child hooked up to a respirator. They were encouraged by the marketers to keep them in a prominent location.

Control: This group received no additional information.

Six months after the baseline survey, all survey respondents took a urine test to determine if they were still smoking. Individuals in the CARES treatment groups would receive their entire balance back if they passed the test, but would forfeit it if they failed or refused to take the test. Non-clients (those assigned to the cues and comparison groups) were paid 30 pesos (US$0.60) for taking the six-month test, and all respondents were paid 30 pesos for taking another test 12 months after the baseline.
Intervention Start Date
2006-08-01
Intervention End Date
2007-05-31
Primary Outcomes
Primary Outcomes (end points)
Smoking status at six month and twelve month after intervention
Primary Outcomes (explanation)
Smoking status checked by NicCheck urine test strip test for nicotine and its primary metabolite, cotinine. The test result provides a categorical measure of recent nicotine consumption, with values ranging from 0 (no exposure) to 15 (high exposure). Only a zero was considered a passing result, and marketers emphasized that clients must stop smoking completely in order to be sure of passing the test.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The experiment was rolled out in three distinct waves of marketing. The probability of assignment to groups in wave 1 was heavily slanted towards CARES to establish whether there was sufficient takeup to proceed with continued research on the product: CARES with deposit – 45%, CARES without deposit – 45%, Cue cards – 5%, and control – 5%. After establishing that there was sufficient take up of CARES, Green Bank changed the assignment probabilities in wave 2 to 15%, 15%, 30%, and 40% for the second wave in order to improve power for identifying the impact of CARES on smoking cessation. In wave 3, a special formula was used to assign the treatment condition which is discussed in the randomization method.

In order to validate the quality and accuracy of information provided by the marketers, field staff from IPA conducted spot-checking visits with randomly selected respondents who had been offered CARES. More than 90 percent of the clients accurately described the main features of the product design.
Experimental Design Details
Randomization Method
Two types of randomization was carried out.
Type 1: After completing the baseline survey, marketers revealed a sticker on the back of the survey that randomly assigned the subject to one of four groups.

Type 2: Marketers used a calculator to solve an equation based on the subject’s birth date (the residual of dd + mm + yy, divided by three). The individual was then assigned to the CARES group if the residual was zero, to cue cards if the residual was one, and to control if the residual was two.
Randomization Unit
Individual smokers
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
2000 individual smokers
Sample size: planned number of observations
2000 individual smokers
Sample size (or number of clusters) by treatment arms
CARES: 781 individuals
Cues: 603 individuals
Control: 616 individuals
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
IRB Approval Date
IRB Approval Number
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
May 31, 2007, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
May 31, 2008, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
1,218 individual smokers
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
1,218 individual smokers
Final Sample Size (or Number of Clusters) by Treatment Arms
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
PUT YOUR MONEY WHERE YOUR BUTT IS: A COMMITMENT CONTRACT FOR SMOKING CESSATION

We designed and tested a voluntary commitment product to help smokers quit smoking. The product (CARES) offered smokers a savings account in which they deposit funds for six months, after which they take a urine test for nicotine and cotinine. If they pass, their money is returned; otherwise, their money is forfeited to charity. Of smokers offered CARES, 11 percent took up, and smokers randomly offered CARES were 3 percentage points more likely to pass the 6-month test than the control group. More importantly, this effect persisted in surprise tests at 12 months, indicating that CARES produced lasting smoking cessation.
Citation
Gin, Xavier, Dean Karlan, and Jonathan Zinman. 2010. "Put Your Money Where Your Butt Is: A Commitment Contract for Smoking Cessation." American Economic Journal: Applied Economics 2: 213-35.