Reactive Sticks A Randomized Control Trial on the Effects of Sunk Costs on Completions Rates of a Substance-Use-Disorder Self-Help Program

Last registered on December 20, 2021

Pre-Trial

Trial Information

General Information

Title
Reactive Sticks A Randomized Control Trial on the Effects of Sunk Costs on Completions Rates of a Substance-Use-Disorder Self-Help Program
RCT ID
AEARCTR-0008713
Initial registration date
December 15, 2021

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
December 20, 2021, 8:51 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Region

Primary Investigator

Affiliation
Amsterdam Law School

Other Primary Investigator(s)

PI Affiliation
Yale Law School
PI Affiliation
Amsterdam University Medical Center Department of Psychiatry

Additional Trial Information

Status
On going
Start date
2021-12-13
End date
2022-03-30
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Online substance-use-disorder treatment programs face the common challenge of keeping individuals committed to their initial goals to complete the program. In this study, we experimentally test the effect of sunk costs on resolve to complete the program and achieve self-set goals. We focus on subjects with use-disorder concerning an array of substances and activities — alcohol, cannabis, gambling, cocaine, smoking — who voluntarily enroll in a free online self-help program consisting of several modules. We manipulate the “cost” of participation in the program by varying the ease with which subjects can (1) start module 1 and (2) transition from module 1 to module 2. We hypothesize that those subjects who faced higher sunk costs of participation will display (1) higher rates of program completion, (2) longer program engagement as compared to a control group, (3) higher rates of achievement of self-set goals, (4) reduced cravings, and (5) higher self-reported motivation. We will also be able to assess whether flat or escalating temptations are more effective in cementing resolve. Finally, we will run a heterogeneity analysis and a voluntary post-experimental survey.
External Link(s)

Registration Citation

Citation
Ayres, Ian, Giuseppe Dari Mattiacci and Anneke Goudriaan. 2021. "Reactive Sticks A Randomized Control Trial on the Effects of Sunk Costs on Completions Rates of a Substance-Use-Disorder Self-Help Program." AEA RCT Registry. December 20. https://doi.org/10.1257/rct.8713
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Experimental Details

Interventions

Intervention(s)
Individuals in the treatment groups will be asked to complete a standard slider task, in order to have subject exert effort in a way that is as uniform as possible across individuals. (Gill & Prowse https://web.ics.purdue.edu/~gill53/GillProwseSliders.pdf)

The task consists of several sliders positioned at 0, which have to be repositioned at the mid-point using the mouse, trackpad or touch screen.

Low-effort version: 20 sliders
High-effort version: 40 sliders
Intervention Start Date
2021-12-13
Intervention End Date
2022-01-31

Primary Outcomes

Primary Outcomes (end points)
Quit rates at intervention points, completion rate and length of engagement with the program (number of modules completed and time elapsed from the start to the last completed task), self-assessment about reaching initially stated goals, self-reported level of cravings, motivation rating at the end of module 1.
Primary Outcomes (explanation)
We will measure the rate of program completion for treatment and control groups as well as the average length of engagement with the program both in terms of the number of modules completed and in terms of the time elapsed from the start of the program to the last completed task. We will assume that an individual has quit the program if he/she has been inactive for 15 days.

Secondary Outcomes

Secondary Outcomes (end points)
heterogeneity analysis
Secondary Outcomes (explanation)
We will run a heterogeneity analysis to see whether the effect (if any) is concentrated in a particular subgroup of the population of subjects. This could be done by leveraging on data from the companion data-science project to identify individuals who are likely to have “weak motivation”. Our previous study shows that those are the ones who are most likely to be benefitted by the intervention.

Experimental Design

Experimental Design
Jellinek offers an online self-help program targeted at individuals that self-report the wish to diminish use or quit alcohol, smoking, cannabis, cocaine or gambling. The program is anonymous and free of charge for participants and consists of several modules

Rough data: 85% fails to finish the program. Yet of the 15% who finishes does not necessarily reach their goal.

At the start, subjects communicate their use and their goal (quit, reduce use, …). At the end, they report their use (hence one can assess whether they reached their goal).

The experiment will run for 1.5 months — from 13 December 2021 to 31 January 2022 — and the data collection will take place until 30 March 2022 in order to follow the performance of all subjects, including those who enrolled towards the end of the trial period.

It is crucial that during this period no changes be made to the program.

Subjects will be randomly allocated to 1 of 4 groups:
1. Control group: Motivation / cravings rating before the start and at the end of module 1.
2. Condition A: At enrollment: motivation / cravings rating followed by low-effort task. At the end of module 1: motivation / cravings rating and no task.
3. Condition B: At enrollment: motivation / cravings rating followed by low-effort task. At the end of module 1: motivation / cravings rating followed by low-effort task.
4. Condition C: At enrollment: motivation / cravings rating followed by low-effort task. At the end of module 1: motivation / cravings rating followed by high-effort task.

The idea of the treatments is to test the effect of having to overcome a small hurdle before being able to go on with the program. Condition A tests the effectiveness of one intervention. Condition B tests whether repeating the effort task a second time further boosts resolve. The first and the second tasks have the same degree of difficulty. Condition C tests the effect of escalating the difficulty of the task from the first to the second intervention.
Experimental Design Details
Randomization Method
Computerized randomization, blocked per condition.
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
We expect a total sample size of about 1200 subjects based on enrollment in 2020 (9255 subjects) and an intervention period of 1.5 months. We expect the sample to be composed as follows: 33% alcohol, 29% smoking, 21% cannabis, 9% cocaine and 8% gambling.
Sample size: planned number of observations
1200 individuals
Sample size (or number of clusters) by treatment arms
300
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
Medisch Ethische Toetsingscommissie AMC University of Amsterdam
IRB Approval Date
2021-12-02
IRB Approval Number
W21_439 # 21.580

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
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