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.