No Time Like the Present: The Effects of On-Demand Trips for Paratransit Customers on Rider Mobility, Wellbeing, and Health

Last registered on August 31, 2026
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Pre-Trial

Trial Information

General Information

Title
No Time Like the Present: The Effects of On-Demand Trips for Paratransit Customers on Rider Mobility, Wellbeing, and Health
RCT ID
AEARCTR-0019519
Initial registration date
August 27, 2026

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 31, 2026, 8:25 AM EDT

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

Locations

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Primary Investigator

Name
Michael Cassidy
Affiliation
Icahn School of Medicine at Mount Sinai
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Other Primary Investigator(s)

PI Name
Ludovica Gazze
PI Affiliation
University of Warwick
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PI Name
Melissa Gentry
PI Affiliation
University of South Florida
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Additional Trial Information

Status
In development
Start date
2027-01-01
End date
2029-12-31
Keywords
Health
Additional Keywords
public transit, transportation, mobility, disability, paratransit, wellbeing, urban
JEL code(s)
J14, J0, R40, R41, R42
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
About a quarter of Americans with disabilities are poor. One contributing factor is a lack of physical mobility, which may limit access to health care, social relationships, and economic participation. Although the Americans with Disabilities Act requires public transit agencies to provide riders unable to use fixed-route transit with paratransit alternatives, paratransit users are generally required to book trips a day in advance, constraining flexibility. In this study, we will conduct a randomized controlled trial of King County Metro’s new Access On-Demand program, which allows paratransit users to book same-day trips. This is the first study to evaluate the effects of an on-demand transportation option on paratransit customers’ mobility, transportation security, health, and wellbeing. The research design, which will leverage administrative data complemented by surveys, is the product of a long collaboration between the research team and King County Metro and is informed by an nonexperimental pilot.
External Link(s)
J-PAL

Registration Citation

Citation
Cassidy, Michael, Ludovica Gazze and Melissa Gentry. 2026. "No Time Like the Present: The Effects of On-Demand Trips for Paratransit Customers on Rider Mobility, Wellbeing, and Health." AEA RCT Registry. August 31. https://doi.org/10.1257/rct.19519-1.0
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Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2027-01-01
Intervention End Date
2028-06-30

Primary Outcomes

Primary Outcomes (end points)
Our primary outcomes span two domains: (1) mobility and transportation security, and (2) health and wellbeing. Our primary mobility outcomes will be trips taken and distance traveled (KCM’s data). Our primary health outcomes will be indicators for any physical health claim, any mental health claim, and spending for each type of claim from the APCD data. Our survey will focus on a pair of validated indices: the University of Michigan’s six-question Transportation Security Index (TSI; Murphy et. al., 2024), and The Human Flourishing Program’s flourishing index (HFI; VanderWeele, 2017; VanderWeele et. al., 2025).
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Eligible riders who complete a baseline survey will be randomized into treatment and control groups. Participants in the treatment group will be offered on-demand paratransit services. All riders will retain access to traditional paratransit.
Experimental Design Details
Not available
Randomization Method
Computer randomization
Randomization Unit
Individual
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
1,500 people
Sample size: planned number of observations
1,500 people
Sample size (or number of clusters) by treatment arms
500 treatment; 1,000 control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Icahn School of Medicine at Mount Sinai
IRB Approval Date
2026-04-17
IRB Approval Number
STUDY-25-01124-MOD001
Analysis Plan