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Commitment Contracts and School Competition for Smoking Prevention in Indonesia
Last registered on July 25, 2017

Pre-Trial

Trial Information
General Information
Title
Commitment Contracts and School Competition for Smoking Prevention in Indonesia
RCT ID
AEARCTR-0001607
Initial registration date
January 19, 2017
Last updated
July 25, 2017 4:23 AM EDT
Location(s)
Primary Investigator
Affiliation
Notre dame
Other Primary Investigator(s)
PI Affiliation
University of California, San Francisco
PI Affiliation
University of Gadjah Mada
PI Affiliation
Kulon Progo District Health Office, University of Gadjah Mada
Additional Trial Information
Status
In development
Start date
2017-01-20
End date
2017-07-31
Secondary IDs
Abstract
Our study presents a novel design to test the effectiveness of nonmonetary incentives and peer pressure
to enforce a health policy. We will ask students and parents to sign an agreement that commits parents to
monitor their children at home and penalizes the students for smoking at school. The penalty is nonmonetary
in nature, thereby making it more sustainable and more easily scalable. In a subset of schools, we also
introduce group competition to test the effectiveness of peer support and pressure for improving health
behavior.
External Link(s)
Registration Citation
Citation
Dewi, Fatwa et al. 2017. "Commitment Contracts and School Competition for Smoking Prevention in Indonesia." AEA RCT Registry. July 25. https://doi.org/10.1257/rct.1607-2.0.
Former Citation
Dewi, Fatwa et al. 2017. "Commitment Contracts and School Competition for Smoking Prevention in Indonesia." AEA RCT Registry. July 25. http://www.socialscienceregistry.org/trials/1607/history/19776.
Experimental Details
Interventions
Intervention(s)
In the treatment group, students will be invited to sign a commitment contract stating that they will
abstain from any tobacco use during the intervention period. Parents will sign a similar contract stating
that they will monitor their children to prevent them from smoking. Students who violate the terms of the
contract, as measured by a biochemically verified test and student and teacher reports, will be penalized
using a school-based demerit point system. The penalty is nonmonetary in nature, improving the chances
that the intervention is sustainable, culturally acceptable, and scalable.
Intervention Start Date
2017-01-20
Intervention End Date
2017-05-31
Primary Outcomes
Primary Outcomes (end points)
Smoking status of students
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The study will target male students in the 7th grade (sekolah menegah pertama), who typically enter the
grade at 12 years old. In our setting, most male students report smoking for the first time at 12-13 years old.
The study only targets male students because smoking is extremely rare among female students in Indonesia.
We will implement a cluster randomized controlled design, where schools serve as the unit of randomization
to minimize the chance of spillover effects.
We used pair matching to randomly allocate schools to intervention arms. Studies have shown that pair
matching outperforms other randomization methods in balancing arms [Imai et al., 2009, Bruhn and McKenzie,
2009]. We formed pairs so as to minimize the Mahalanobis distance between the values of selected covariates
within pairs. We then randomly assigned one unit to the treatment group and one unit to the control group.
Among the treatment group schools, we then paired the two most similar schools by Mahalonobis distance
and randomly assigned one to the commitment arm and one to the commitment plus competition arm. Thus,
we randomly allocated 36 schools to the control arm, 18 schools to the commitment arm, and 18 schools to
the commitment plus competition arm.
Our matching procedure will include the following covariates: district, subdistrict, distance from the
school to Yogyakarta proper, number of male students and classrooms in 7th grade, total number of students,
teachers, classes, and student council members in the school, electricity capacity, and average national
exam scores in mathematics.
We test for balance along pre-intervention characteristics using a t-test of equality across arms and in
bivariate comparisons that regress each covariate on a dummy equal to one if the intervention was implemented
in the school.
Experimental Design Details
Randomization Method
We used pair matching to randomly allocate schools to intervention arms. The matching
procedure will be performed in R.
Randomization Unit
Schools
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
72 schools
Sample size: planned number of observations
We anticipate having a sample size of 2,500 students.
Sample size (or number of clusters) by treatment arms
36 schools to the control arm, 18 schools to the commitment arm, and 18 schools to
the commitment plus competition arm.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The pairwise comparisons indicate that the study has sufficient power to detect differences in the probability of smoking of a 5-percentage point magnitude or greater compared to the control arm.3 Using this minimum detectable effect, the study will have 80% power to detect an intervention-related reduction in smoking rates for the treatment group with a sample size of 72 schools. We adopted the following assumptions for the calculations: • Type-I error of = 0.05. • A plausible range of values for the probability of smoking in the control arm of 5% to 25%, with a mean expected value of 10%, based on national survey data and our pilot work • An average of 30 participating students per school (geometric mean)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
University of Gadjah Mada
IRB Approval Date
2016-09-13
IRB Approval Number
KE/FK/1018/EC/2016
IRB Name
Nanyang Technological University
IRB Approval Date
2015-09-22
IRB Approval Number
IRB-2015-04-009
Analysis Plan

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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