Messages on Self or Social Cost of End of Year Medicine Stock Up

Last registered on December 07, 2020


Trial Information

General Information

Messages on Self or Social Cost of End of Year Medicine Stock Up
Initial registration date
December 06, 2020

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 07, 2020, 10:54 AM EST

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



Primary Investigator

UC San Diego

Other Primary Investigator(s)

PI Affiliation
Chinese Academy of Social Sciences

Additional Trial Information

In development
Start date
End date
Secondary IDs
As an effort to promote access to healthcare services and products, people usually face an out-of-pocket price that is lower than the true marginal cost, which leads to overuse. Traditional approach to this problem would be to increase price, but in healthcare setting it is in conflict with the first order importance of access. In this project we study whether non-monetary approaches - text message nudges on rational healthcare utilization could make a difference. Since the overuse is neither individually nor socially efficient, we will test whether people respond to self and social aspect nudges.
External Link(s)

Registration Citation

He , Daixin and Jianan Yang. 2020. "Messages on Self or Social Cost of End of Year Medicine Stock Up." AEA RCT Registry. December 07.
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
December 2020 Spending
December 2020 Spending relative to Jan-Nov Monthly Average
December 2020 Medicine Spending and Dosage Purchased: Breakdown by Acute/Chronic Condition Medicine
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
2021 monthly spending, medicine purchases and acute/chronic condition medicine breakdown
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Each individual in our sample will be randomly assigned to one of the three groups: two treatment groups and one control group. The control group will receive a placebo message, which only provides a simple reminder for reasonable use of healthcare services and health insurance. The “self-cost” treatment group receives message with information on the potential self monetary cost of medicine stock up - it might lead to medicine expiration before them being properly used. And the other group will receive “social cost” messages, which states how the expired medicine might cause a waste of resources, damage to the environment and imposes a burden on the public health care fund.
Experimental Design Details
Randomization Method
We will conduct a stratified randomization based on gender, age, and past healthcare utilization patterns using STATA.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
No cluster design
Sample size: planned number of observations
Around 16,000 individuals
Sample size (or number of clusters) by treatment arms
Around 5,300 individuals in control and each of the two treatment groups
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We expect the Minimum Detectable Effect (MDE) to be 0.054 standard deviation. This MDE is equivalent to around 10.4% drop in December spending between the treatment groups and the placebo group.

Institutional Review Boards (IRBs)

IRB Name
Internal Board at FinanLab, Chinese Academy of Social Sciences
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials