Intervening with Consumers to Improve Choices on Health Insurance Marketplaces
Last registered on April 11, 2018


Trial Information
General Information
Intervening with Consumers to Improve Choices on Health Insurance Marketplaces
Initial registration date
March 23, 2016
Last updated
April 11, 2018 1:28 PM EDT
Primary Investigator
Columbia University
Other Primary Investigator(s)
PI Affiliation
Wakely Consulting
PI Affiliation
Harvard Medical School
PI Affiliation
Boston University Questrom School of Business
Additional Trial Information
Start date
End date
Secondary IDs
The Affordable Care Act dramatically expanded the use of regulated marketplaces to provide individuals with health insurance coverage. The efficiency of these marketplaces depends on the ability of consumers to choose plans that reflect their preferences, but inattention and information frictions may inhibit optimal choices. This study is a 3-arm randomized intervention to test for the presence of frictions in plan choice and to see if certain strategies to communicate with consumers can reduce these frictions. The implementing partner is the Colorado ACA marketplace, Connect for Health Colorado. In the study, we send simple, salient information about plan premiums to re-enrolling consumers. One study group receives e-mails and letters containing generic information about the potential premium savings from shopping, while another group is sent similar but personalized materials that project their savings based on their previous year’s income and household structure. A third group receives no intervention materials and acts as a control. We will track the effects of these letters on shopping behavior using administrative data from the marketplace. We will test the effect of the generic and personalized information on whether an individual switches her plan, how much she pays in premiums, and her elasticity of plan choice with respect to premiums. The results of this study will provide reduced form evidence on the size of behavioral frictions in health insurance relating to plan premiums. The study will also provide evidence on inexpensive, effective strategies for Marketplaces and policymakers to help consumers select health plans that more closely reflect their preferences.
External Link(s)
Registration Citation
Ericson, Keith et al. 2018. "Intervening with Consumers to Improve Choices on Health Insurance Marketplaces." AEA RCT Registry. April 11.
Former Citation
Ericson, Keith et al. 2018. "Intervening with Consumers to Improve Choices on Health Insurance Marketplaces." AEA RCT Registry. April 11.
Sponsors & Partners

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Experimental Details
"As-usual" intervention: No additional materials were sent to the members.

Control Intervention: We send two generic letters and two e-mails telling individuals that they should actively shop for plans on the marketplace. The materials do not contain any information that is specific to the recipient, and will be based on standard communications templates that the marketplace already uses.

Premium Savings Intervention: We modify the generic letters and e-mails to include information about the maximum the individual can save compared to her current plan by switching plans on the marketplace, and send the customized communications. The savings calculation will be adjusted for the subsidies that the consumer can expect to receive based on the most recent information she has provided to the marketplace. The savings are presented as the difference in price relative to what the member would pay in her current plan, if she were to stay enrolled in it in 2016.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Active shopping on the exchange
Switching to another plan
The realized premium of the member's 2016 plan
The realized cost-sharing of the member's 2016 plan
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The set of marketplace members who were eligible for automatic re-enrollment for 2016 was identified by the marketplace. We then limited this sample to members who could potentially save on premiums by switching to another plan in their metal tier. The remaining members became the study sample, and they were randomly allocated to three arms:
1. No intervention
2. Control intervention
3. Premium Savings intervention
Experimental Design Details
Randomization Method
Randomization done by computer (in Stata)
Randomization Unit
Connect for Health Colorado account (i.e. household) level
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
5,000 per arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Office of Human Research Administration
IRB Approval Date
IRB Approval Number
Analysis Plan
Analysis Plan Documents
Prespecified Analysis Plan - March 31, 2016

MD5: 72bd412d59ad9d45c654a688fc1fafb0

SHA1: c10822d1595d4139d723071c7f38230129ea58c0

Uploaded At: April 20, 2016

Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)