Methods: Mind the Gap

Webinar Series

Designing Stepped Wedge Trials with Continuous Recruitment

July 21, 2022, 12:00 p.m. ET
Richard Hooper
Richard Hooper, Ph.D.

Queen Mary University of London, UK

*A recording of this webinar will be available approximately two weeks after the session.

About the Webinar

When a stepped wedge or other longitudinal cluster-randomized trial recruits or identifies participants in a continuous stream over a given calendar period, it is quite different to sampling in a series of discrete, cross-sectional slices. For one thing, introducing an intervention midstream to a cluster could contaminate participants recently recruited under the routine care condition. For another, it is no longer helpful to speak of distinct time “periods”—two individuals recruited at either end of the “same” period may have less in common than two individuals recruited just on either side of a “division” between periods. A continuous timescale also offers a continuously adaptable framework for designing a longitudinal trial—timing when to intervene, and when to start or stop recruitment in different clusters. In this presentation, Dr. Hooper will focus on optimal solutions to three very different design problems for longitudinal cluster trials: (1) a parallel groups design with a prospective baseline period in both arms, (2), a stepped wedge design where each of a large number of clusters may cross over to the intervention at a different time, and (3) an incomplete stepped wedge design where he restricts recruitment to particular time intervals in particular clusters to minimize the burden of participation.

About Richard Hooper

Dr. Richard Hooper is a Professor of Medical Statistics at Queen Mary University of London, UK. He has a 30-year career in health services research as a medical statistician. His current research program aims at driving innovation in the design of randomized evaluations of health interventions and quality improvement programs, including stepped wedge trials and other novel approaches to clustered trials, an area in which he has established an international reputation. In 2019, he was awarded a senior fellowship by The Healthcare Improvement Studies Institute, UK, to develop and promote innovation in trial design as a key aspect of health improvement science. He is the Co-Director of the Pragmatic Clinical Trials Unit at Queen Mary University of London, a UK registered Clinical Trials Unit that specializes in evaluating interventions as they would be delivered by health services.


This webinar will be captioned in real time. Individuals needing reasonable accommodations should contact Taylor Buffa at MindtheGap@od.nih.gov. Requests should be made at least 5 business days before the event.

Last updated on June 22, 2022