How Does Public Environmental Information Shape Demand for Mitigation and Individual Exposure Assessment: A Survey Experiment on Water Lead (Pb) Exposure

Last registered on September 18, 2025
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Pre-Trial

Trial Information

General Information

Title
How Does Public Environmental Information Shape Demand for Mitigation and Individual Exposure Assessment: A Survey Experiment on Water Lead (Pb) Exposure
RCT ID
AEARCTR-0016286
Initial registration date
August 05, 2025

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
August 08, 2025, 7:15 AM EDT

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

Last updated
September 18, 2025, 9:42 PM EDT

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

Locations

Country
United States of America
Region

Primary Investigator

Name
Fanyu Wang
Affiliation
Columbia University
Contact Primary Investigator

Other Primary Investigator(s)

PI Name
Siyuan Hu
PI Affiliation
University of Wisconsin-Madison
Contact Investigator

Additional Trial Information

Status
In development
Start date
2025-09-03
End date
2025-10-31
Keywords
Environment & Energy
Additional Keywords
JEL code(s)
Q53
Secondary IDs
Prior work
This trial is based on or builds upon one or more prior RCTs.
Abstract
Lead exposure from drinking water remains a critical public health concern in the U.S., primarily driven by lead service lines (LSLs)—lead pipes connecting water mains to buildings. Because LSL inventories offer only a proxy for household-level exposure, as tap water lead levels vary with pipe condition and corrosion control, we are motivated to investigate the following three questions. (1) How does receiving public information that serves as a proxy for pollution exposure affect individuals’ beliefs about personal exposure and confidence in those beliefs?
(2) How does it affect willingness to pay (WTP) for mitigation measures? (3) How does it affect WTP for individualized exposure assessments?
Leveraging the newly released LSL inventories, we conduct a survey experiment to study how receiving LSL information shapes perception of exposure and demand for mitigation and individualized exposure assessment. Survey participants are randomly assigned to receive either general EPA information (control) or additional information on whether their residential building has an LSL (treatment). Participants in the treatment arm are explicitly told that the LSL information is extracted from a city government database. The study measures key outcomes before and after the intervention: beliefs about LSL presence in their residential building, beliefs about tap water lead levels, confidence in these beliefs, WTP for lead-filtering pitchers, WTP for professional tap water lead testing, and WTP for pipe replacement.
External Link(s)

Registration Citation

Citation
Hu, Siyuan and Fanyu Wang. 2025. " How Does Public Environmental Information Shape Demand for Mitigation and Individual Exposure Assessment: A Survey Experiment on Water Lead (Pb) Exposure." AEA RCT Registry. September 18. https://doi.org/10.1257/rct.16286-1.1
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Leveraging the newly released building-specific water service line datasets, this study will conduct an information provision experiment in several populated cities with prevalence of LSLs in the Midwest and the Northeast, using an online survey

In the information intervention, the control group will receive general information about the EPA’s requirement for public water systems to notify customers about LSLs. The treatment group will receive the same general information, plus building-specific details about whether their home’s service line is made of lead, retrieved from the city’s official inventory.
Intervention (Hidden)
Geospatial data on water service line inventories have been collected from government websites for each city.
A total of about 1,500 participants will be recruited through CloudResearch and randomly assigned in equal shares to treatment and control groups using Qualtrics’ randomizer. To ensure balance across locations, stratified randomization will be implemented using each city as a separate stratum. The sample size is determined based on a power calculation using data from the previous iteration conducted in NYC. With 1,500 participants equally divided between treatment and control groups, the study achieves the statistical power of 80% to detect a treatment effect of 14% of a standard deviation at the 5% significance level.
Participants will be screened and assigned a water service line material type through a two-step geospatial matching process. First, participants will pinpoint their residence on an embedded interactive map using Qualtrics-Map with Mapbox. Then, the latitude and longitude coordinates from the pinned location will be automatically cross-referenced with the geospatial water service line inventory dataset of the corresponding city. If no match is found, the participant will be screened out. If a match is found, they will continue with the survey. Information about demographics and water usage is collected before the screening question.
Providing identical general information to both groups controls for the potential salience effect of making participants more aware of LSL issues.

The study measures several key outcomes before and after the intervention, including beliefs about LSL presence, tap water lead levels, confidence in these beliefs, WTP for a lead-filtering pitcher, and WTP for a professional kitchen tap water lead test.

To elicit WTP in an incentive-compatible manner, the study uses the Becker-deGroot-Marschak (BDM) method. All participants completing the survey will receive a participation payment. Additionally, two participants will be randomly selected to receive $150 Amazon gift card bonuses. The selected participants will have the option to trade part of their gift card for a kitchen tap water lead inspection or a lead-filtering pitcher. A price is randomly drawn from the interval [0,150]. If the participant’s stated WTP is greater than or equal to the drawn price, they receive the chosen product and a gift card worth the remaining amount after the purchase; otherwise, they receive the full $150 gift card without the product. The participants are informed that if they are chosen to win the bonus, it will be randomly determined which products they will receive.
Intervention Start Date
2025-09-03
Intervention End Date
2025-10-31

Primary Outcomes

Primary Outcomes (end points)
The study measures key outcomes before and after the intervention: beliefs about LSL presence in their residential building, beliefs about tap water lead levels, confidence in these beliefs, WTP for lead-filtering pitchers, WTP for professional tap water lead testing, and WTP for pipe replacement. The first two WTPs are elicited using an incentive-compatible mechanism based on Becker et al. (1964).
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Participants will be screened and assigned a water service line material type through a geospatial matching process. The treatment group will be provided with information on whether their building's service lines are made of lead. Both the treatment and control groups will answer questions about their beliefs regarding whether their homes have LSLs, the safety level of the tap water, their WTP for water filters, and their WTP for kitchen tap water lead concentration inspections.
Experimental Design Details
Randomization Method
Randomization done through Qualtrics randomizer.
Randomization Unit
Individual respondents of the survey.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1500 respondent
Sample size: planned number of observations
1500 respondent
Sample size (or number of clusters) by treatment arms
750 respondents control, 750 respondents treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Minimal Risk Research IRB
IRB Approval Date
2025-08-05
IRB Approval Number
2025-0985-CP001
Analysis Plan

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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