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Targeting Incentive Contracts in Heterogeneous Populations
Last registered on September 20, 2019

Pre-Trial

Trial Information
General Information
Title
Targeting Incentive Contracts in Heterogeneous Populations
RCT ID
AEARCTR-0004735
Initial registration date
September 19, 2019
Last updated
September 20, 2019 9:46 AM EDT
Location(s)

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Primary Investigator
Affiliation
MIT
Other Primary Investigator(s)
PI Affiliation
University of Chicago Booth
Additional Trial Information
Status
On going
Start date
2019-05-01
End date
2021-12-31
Secondary IDs
Abstract
Providing financial incentives to encourage behavioral change is increasingly common: policymakers pay people to exercise, to study more, and maintain tree cover. In designing incentives for behavior change, there is frequently a tradeoff between motivating those with high and low costs of engaging in the behavior: whereas the optimal contract for high-cost individuals will have a large incentive or a low behavior target, the optimal contract for low-cost individuals will have a small incentive or a large behavior target. This project will investigate methods for targeting incentive contracts for behavioral change to individuals with heterogeneous behavior cost. In a randomized controlled trial among individuals with diabetes and prediabetes, we will experimentally evaluate two methods for targeting incentive contracts for walking: individual contract choice, and targeting on observable characteristics. We will first show that in our setting, contracts with a higher step target are more effective for individuals with low walking costs at baseline. Second, we will assess the relative performance of our two targeting methods in terms of targeting precision and walking encouragement. Finally, we will explore the role of key challenges to implementing each method, including the endogeneity and limited information content of observable characteristics, and the principal and agent’s imperfect knowledge of preferences.
External Link(s)
Registration Citation
Citation
Dizon-Ross, Rebecca and Ariel Zucker. 2019. "Targeting Incentive Contracts in Heterogeneous Populations." AEA RCT Registry. September 20. https://doi.org/10.1257/rct.4735-1.0.
Experimental Details
Interventions
Intervention(s)
Intervention Start Date
2019-05-20
Intervention End Date
2020-12-31
Primary Outcomes
Primary Outcomes (end points)
Daily steps taken during intervention.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Indicators for daily steps above 10,000, 12,000, and 14,000; Distance from assigned step target to “optimal” step target; step target assigned; steps taken during “phase-in period”.
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
We randomly assign individuals to one of three targeting regimes: choice, targeting on observables, and random assignment. In addition, a small monitoring group is included for benchmarking purposes; this group will not receive any incentive contract, but we will monitor their steps. We will cross-randomize information on which step target we believe is most likely to be most effective at encouraging walking.
Experimental Design Details
Not available
Randomization Method
Randomization is stratified based on our forecasted median age (49) and gender. Ordered treatment assignment lists for each stratum cell are randomly generated in the office by a computer using Stata 15, and treatments are assigned to participants on rolling basis.
Randomization Unit
Individual
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
1
Sample size: planned number of observations
We aim to enroll approximately 3,500 – 4,500 diabetics and pre-diabetics. We will continue enrollment in this range as our funding allows.
Sample size (or number of clusters) by treatment arms
The following treatment group distribution is approximate, since enrollees will be assigned to treatments according to baseline strata in a pre-determined order, and some may withdraw following randomization but prior to the intervention.
Incentive Groups:
T1 – Random, 10,000 step target: 15%
T2 – Random, 12,000 step target: 25%
T3 – Random, 14,000 step target: 15%
T4 – Choice 1: 25%
T5 – Choice 2: 0.5%
T6 – Targeting: 17.5%

Non-incentive Group:
Monitoring Only: 2%

Information Treatment:
50% of the experimental sample excluding the Targeting group will be cross-randomized into the Information treatment prior to deciding which contract they prefer in Choice Menu 1.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
AURA IRB at University of Chicago
IRB Approval Date
2019-02-26
IRB Approval Number
IRB19-0005