Motivated beliefs and overconfidence in health insurance: a survey study with married individuals

Last registered on May 07, 2025
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Pre-Trial

Trial Information

General Information

Title
Motivated beliefs and overconfidence in health insurance: a survey study with married individuals
RCT ID
AEARCTR-0011139
Initial registration date
May 08, 2023

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
June 23, 2023, 3:38 PM EDT

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

Last updated
May 07, 2025, 10:34 PM EDT

Last updated is the most recent time when changes to the trial's registration were published.

Locations

Country
China
Region
Beijing

Primary Investigator

Name
Chang Zhang
Affiliation
the School of Economics, Peking University
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Other Primary Investigator(s)

PI Name
Ruo Jia
PI Affiliation
School of Economics, Peking University
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PI Name
Jiakun Zheng
PI Affiliation
AMSE, Aix Marseille University
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PI Name
Jiawei Mo
PI Affiliation
School of Economics, Peking University
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Additional Trial Information

Status
Completed
Start date
2023-05-09
End date
2023-07-03
Keywords
Behavior
Additional Keywords
Motivated beliefs, Overconfidence, Decisions between spouses, Household finance
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We conduct a survey-based experiment to examine health insurance demand and overconfidence in health among married individuals. The aim is to provide direct evidence that individuals are overconfident about their own and their spouse's health risks and that they believe they are healthier than their spouses. Additionally, we will investigate how individuals update health-related information about themselves compared to their spouses. The questionnaire comprises six parts. The first module aims to collect basic demographic data from respondents, including their gender, number of children, and weekly exercise time, as well as the same information about their spouses. The second module aims to elicit respondents' perceptions of the health risks. We ask respondents to compare their own health risks with those of their spouses, their own health risks with those of average people in their age and gender group, and their spouses' health risks with those of average people in their spouses' age and gender group. The third module introduces a survey experiment on belief updating. The fourth module collects health information on both respondents and their spouses. The fifth module gathers data on respondents' education levels, lifestyle habits, risk preferences, and private insurance purchases. Finally, the sixth module addresses potential experimenter demand effects; and we inquire whether the respondents trust the cancer news presented in the survey experiment and the extent to which they find others' health information helpful in shaping their beliefs about their own and their spouses' health risks.
External Link(s)

Registration Citation

Citation
Jia, Ruo et al. 2025. "Motivated beliefs and overconfidence in health insurance: a survey study with married individuals." AEA RCT Registry. May 07. https://doi.org/10.1257/rct.11139-2.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
We work on the following stages for both subjects and the spouses of the subjects.

In the first stage, we randomly selected 9 people at the subjects’ gender and age from previous surveys. And ask the subjects’, "Of the 10 people, including you, what do you think the chance is that your odds of getting cancer is higher than half of them (5 selected people)?"

In the second stage, we then present a piece of health-related news to the subjects. Recent studies published in top international oncology journals have shown that increasing physical activity can significantly lower the risk of developing many types of cancer. Specifically, engaging in at least 3 hours of moderate-intensity exercise per week has been shown to reduce the incidence of liver cancer by 27%, lung cancer by 26%, and breast cancer by 10%. Afterward, we asked subjects to choose one of the previously selected 9 people and informed them about how much that person exercises each week. We then asked for their perceived chance that their odds of getting cancer is higher than half of the 10 people again.

The updating order of self and spouse is randomized but consistent in the two stages.
Intervention (Hidden)
Intervention Start Date
2023-05-09
Intervention End Date
2023-07-03

Primary Outcomes

Primary Outcomes (end points)
Perceived likelihood of hospitalization; Updates on perceived cancer risk
Primary Outcomes (explanation)
Updates on perceived cancer risk is the absolute difference in perceived cancer risk before and after the news was provided.

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
To compare the perceived health risks, we inquire about individuals' perceived likelihood of being hospitalized due to illness in the next year, in comparison to people of their age and gender, for both themselves and their spouses. We expect that on average, individuals believe that both themselves and their spouses are healthier than the general population with the same age and gender.

To compare perceived health risks, we also inquire about participants' perceived cancer risk and that of their spouses. Specifically, we ask about the likelihood that participants think they or their spouses are healthier than a half of selected people of their age and gender in terms of cancer risk. We anticipate that, on average, individuals will perceive themselves and their spouses to be healthier than a half of people in terms of cancer risk. We then demonstrate the high correlation between the two measures of overconfidence.

To compare individuals with their spouses, we ask participants, "Compared to your spouse, how likely do you think you are to be hospitalized due to illness in the next year?" We expect to find that, on average, individuals perceive themselves as healthier than their spouses.

To capture the information updating process, we present a piece of health-related news. Before and after sharing the news, we ask participants about their perceived chance that their and their spouses odds of getting cancer is higher than a half of the 10 people. We then compare the participants' response to the news when estimating their own and their spouses’ cancer risk.
Experimental Design Details
Randomization Method
All randomization is within subject, done by the computer.

Clarification on random assignment: This is a within-subjects design. That is, some subjects first update the information for themselves and others update the information of their spouses. The updating order of self and spouse is randomized by a computer.
Randomization Unit
Individual.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
2000 married individuals.
Sample size: planned number of observations
4000 individuals, that is 2000 married individuals and their spouses.
Sample size (or number of clusters) by treatment arms
This is a within-subjects design and it has an information treatment.
Subjects will update information for both themselves (2000 individuals for control) and their spouses (2000 individuals for treatment).
We also compare subjects' beliefs before information treatment (for control) and after giving health-related information (for the treatment group).
For the good-bad news effect, about 1000 subjects receive good news for the control and 1000 subjects receive bad news for the treatment group.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Lab of National Governance and Development, Renmin University of China
IRB Approval Date
2023-03-23
IRB Approval Number
RUCecon-202304-2
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
Yes
Intervention Completion Date
July 03, 2023, 12:00 +00:00
Data Collection Complete
Yes
Data Collection Completion Date
July 03, 2023, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
2000 married individuals.
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
4000 individuals, that is 2000 married individuals and their spouses.
Final Sample Size (or Number of Clusters) by Treatment Arms
This is a within-subjects design and it has an information treatment. Subjects will update information for both themselves (2000 individuals for control) and their spouses (2000 individuals for treatment).
Data Publication

Data Publication

Is public data available?
No

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Program Files

Program Files
No
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials