The Last Meter: Incentivizing Lead Water Service Line Inspections among Hard-to-Reach Populations in Trenton, NJ.

Last registered on June 26, 2023

Pre-Trial

Trial Information

General Information

Title
The Last Meter: Incentivizing Lead Water Service Line Inspections among Hard-to-Reach Populations in Trenton, NJ.
RCT ID
AEARCTR-0010330
Initial registration date
October 28, 2022

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
October 31, 2022, 4:38 PM EDT

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

Last updated
June 26, 2023, 2:10 PM EDT

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

Locations

Primary Investigator

Affiliation
University of Warwick

Other Primary Investigator(s)

PI Affiliation
University of Warwick
PI Affiliation
University of Chicago
PI Affiliation
University of Chicago
PI Affiliation
National Center for Environmental Economics, US Environmental Protection Agency
PI Affiliation
National Center for Environmental Economics, US Environmental Protection Agency
PI Affiliation
National Center for Environmental Economics, US Environmental Protection Agency

Additional Trial Information

Status
In development
Start date
2022-07-26
End date
2024-01-08
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Despite federal law banning the use of new lead service lines in drinking water systems for decades due to their detrimental health effects, an estimated 9.7 to 12.8 million legacy lead service lines (LSLs) connect water mains to homes in the United States (NRDC 2021). Many public water systems are struggling to locate and replace lead pipes with safe alternatives, particularly due to the scale of the problem and persistent challenges of gaining cooperation from some segments of the population.

The purpose of this study is to investigate the efficacy of interventions designed to overcome the barriers public water systems face when trying to locate lead service lines in these “hard-to-reach” populations. In partnership with Trenton Water Works, a major public utility in Trenton, New Jersey, we will test several different interventions encouraging members of these “hard-to-reach” populations to submit a simple “self-inspection” of their pipes (consisting primarily of photos of the pipes) to the utility to help them locate lead on the private, homeowner side of the service line.
External Link(s)

Registration Citation

Citation
Gazze, Ludovica et al. 2023. "The Last Meter: Incentivizing Lead Water Service Line Inspections among Hard-to-Reach Populations in Trenton, NJ. ." AEA RCT Registry. June 26. https://doi.org/10.1257/rct.10330-1.1
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
This project studied several interventions designed to encourage addresses to make use of the local lead service line self-inspection program, which allows residents to submit photos of their service lines to have their material identified. Addresses will be assigned to one of the following treatments: an informational treatment consisting of distributed materials explaining the program, or a financial incentive treatment consisting of the same materials, but with the offer of a gift card reward for participating in the program.

Addresses that do not respond to treatment after one month will receive one of the following cross-randomized treatment enhancements to allow us to estimate the costs and impacts of varied treatment intensities to inform policy feasibility at scale in Phase 2: either a repeat of their original treatment, or in-person follow-up by field staff offering to help them complete the self-inspection.

Intervention Start Date
2023-01-09
Intervention End Date
2023-05-29

Primary Outcomes

Primary Outcomes (end points)
Participation in lead service line self-inspection program
Primary Outcomes (explanation)
Inspection participation will be measured as submission of self-inspection service line photos that are of adequate quality to ascertain pipe material between the start of the intervention and the end of the intervention period.

Secondary Outcomes

Secondary Outcomes (end points)
Water service line material
Secondary Outcomes (explanation)
Water service line material, on the private side of the service line, will be determined from professional review of the submitted self-inspection, and grouped by either "contains lead" or "does not contain lead."

Experimental Design

Experimental Design
This study focuses on the impact of different outreach and engagement methods designed to encourage households to submit a self-inspection of their service lines to help the local utility identify which addresses have lead service lines connecting them to the water system.

Each address in our sample of 9,000 is assigned to one of three roughly equal-sized experimental groups of 3,000 addresses – Treatment 1 (information only), Treatment 2 (information and financial incentive), or Control (no further outreach or incentive). Participating households will submit photos of their service line online, following instructions to ensure they are of sufficient quality for trained staff to identify the service line material.

For Phase 2, after one month, we will randomize all addresses that were assigned to Treatment 1 or 2 but did not respond to the intervention into one of three, equal-sized, cross-randomized, secondary treatments – Secondary Treatment 1 (repeat initial treatment), Secondary Treatment 2 (in-person follow-up), or Control (no additional treatment). In the in-person follow-up, staff will make several attempts to make contact with the resident, and will offer to assist them in completing the self-inspection, including providing a device to use for taking and submitting the photos.

We will principally examine the difference in uptake between each of these interventions and the control. We will also compare the difference in uptake between different levels of financial incentive to trace demand curves for the program, and will examine the prevalence of lead among respondents at different levels of incentive to assess if households that already know they do not have lead are less likely to participate in the absence of a high incentive.
Experimental Design Details
This study focuses on the impact of different outreach and engagement methods designed to encourage households to submit a self-inspection of their service lines to help the local utility identify which addresses have lead service lines connecting them to the water system.

Each address in our sample of 9,000 is assigned to one of three roughly equal-sized experimental groups of 3,000 addresses – Treatment 1 (information only), Treatment 2 (information and financial incentive), or Control (no further outreach or incentive). Addresses assigned to Treatment 2 will be further randomly assigned to one of four incentive levels: $10, $25, $50, or $100. In Phase 1, each household will receive a door hanger that either only has information about the program, or that offers them one of the described financial incentives. Participating households will go to the website indicated on the door hanger and submit photos of their service line, following instructions to ensure they are of sufficient quality for trained staff to identify the service line material. Households will receive their gift card reward automatically upon verification that their photos are of sufficient quality to have the service line material verified.

For Phase 2, after one month, we will randomize all addresses that were assigned to Treatment 1 or 2 but did not respond to the intervention into one of three, equal-sized, cross-randomized, secondary treatments – Secondary Treatment 1 (repeat initial treatment), Secondary Treatment 2 (in-person follow-up), or Control (no additional treatment). In the in-person follow-up, staff will make several attempts to make contact with the resident, and will offer to assist them in completing the self-inspection, including providing a device to use for taking and submitting the photos.

We will principally examine the difference in uptake between each of these interventions and the control. We will also compare the difference in uptake between different levels of financial incentive to trace demand curves for the program, and will examine the prevalence of lead among respondents at different levels of incentive to assess if households that already know they do not have lead are less likely to participate in the absence of a high incentive.

Randomization Method
Randomized assignment before treatment done in office by a computer
Randomization Unit
Residential address
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
9,000 residential addresses
Sample size: planned number of observations
9,000 residential addresses
Sample size (or number of clusters) by treatment arms
Control: 3,000 residential addresses
Treatment 1 (information only): 3,000 residential addresses
Treatment 2a ($10 incentive): 875 residential addresses
Treatment 2b ($25 incentive): 875 residential addresses
Treatment 2c ($50 incentive): 750 residential addresses
Treatment 2d ($100 incentive): 500 addresses
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We are powered to detect a 2.28 percentage point increase in the rate of uptake in the treatment groups for Treatment 1 or Treatment 2 (i.e. an increase of 68 more households participating in the program), with 80% power and alpha 0.05.
IRB

Institutional Review Boards (IRBs)

IRB Name
University of Chicago Institutional Review Board
IRB Approval Date
2022-07-26
IRB Approval Number
IRB22-1087
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