Experimental Design
Two-arm, individual-level randomized controlled trial delivered through Link Health's remote benefits-assistance channel. Each partner CHC texts its own patients, from its own platform, about free help enrolling in public benefits; the message carries a link coded to that health center and to the outreach language. Tapping the link is the single entry action: the study server logs the click, assigns the arm, and opens the participant's messaging app with a short text pre-filled, carrying the assignment code, addressed to the assigned arm's Link Health number; no page or form is shown and no phone number is entered. The mechanic is identical in both arms.
- **AI arm.** An SMS conversation with LEO, Link Health's AI enrollment assistant (inference on AWS Bedrock; SMS on Amazon SNS with AWS End User Messaging, in Link Health's AWS environment — a study build, since LEO's operational deployment is a web chat). LEO identifies itself as automated, delivers the research disclosure, screens for eligibility, completes applications conversationally, and submits through Link Health's standard human-review step. Participants may reach a human at any time on request; LEO also hands off on distress flags and fallback thresholds.
- **Human navigator arm.** An SMS conversation, on the same service, with a Link Health remote navigator, whose first message carries a one-line self-introduction and the same disclosure; the navigator screens, assists, and submits through the same review step.
**Service levels.** The AI arm is continuously available and responds immediately, in English and Spanish. The human arm is staffed by 5–20 trained navigators per campaign, shifts between 8am and 8pm Central, response fulfillment targeted within 48 hours of a wave — the service levels as currently staffed; the levels in force at launch are confirmed then and reported with the results. The asymmetry is part of the treatment as it exists: the estimand is the two modalities *as deployed*, service levels included, and response latency differs between arms by construction — an interpretive point for the process outcomes, not a limitation to adjust away. A participant who stalls or abandons mid-application receives, at minimum, follow-ups at approximately 48 hours and 7 days, in both arms, on an identical schedule, delivered channel-natively; the schedule is a floor — if Link Health's documented standard follow-up practice is denser, that practice becomes the floor, applied identically in both arms.
**What is and is not contrasted.** The arms differ in *who or what* provides the assistance and in nothing else the study controls: both are SMS conversations on Link Health's numbers, entered by the same tap-to-text mechanic, carrying the same four-message disclosure, with the same follow-up schedule and the same outcome contact. The estimand is AI assistance versus human assistance with the channel held constant — the modalities as deployed, service levels included. Both arms are new SMS deployments for the study (LEO's SMS delivery; the navigator pathway), which is what the QA wave exists to verify (§5).