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Featured collection: Sample size calculations and specifying the target difference for randomized trials

This new article collection includes the DELTA2 guidance on the specification and reporting of the target difference and the sample size calculation for a RCT, along with articles on how it was developed, previous guidance on this topic, a review of practice in a cohort of RCTs and a commentary on the value of the new guidance.

Announcement: we are recruiting new Associate Editors

We are recruiting new Associate Editors to join our international Editorial Board, helping to provide expertise on the design, conduct and reporting of trials in our journal.

Click here to find out more.


  1. Content type: Research


    Authors: Jo Howard, Sophie A. Lee, Baba Inusa, Man Ying Edith Cheng, Cheema Bavenjit, Isabel C. Reading, Sally Ann Wakeford, Johanna C. Gavlak, Patrick B. Murphy, Nicholas Hart, Atul Gupta, Sati Sahota, Eufemia Jacob, Maria Chorozoglou, Carol Ossai, Maureen Gwam…

  2. Content type: Study protocol


    Authors: Larissa Jennings Mayo-Wilson, Nancy E. Glass, Fred M. Ssewamala, Sebastian Linnemayr, Jessica Coleman, Fatmata Timbo, Matthew W. Johnson, Melissa Davoust, Alain Labrique, Gayane Yenokyan, Brian Dodge and Carl Latkin

  1. Content type: Review


    Authors: Barbara Farrell, Sara Kenyon and Haleema Shakur

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Article collections

Article collection
Sample size calculations and specifying the target difference for randomized trials

Thematic series
Building capacity for evidence informed trial management
Edited by Dr Roberta Littleford and Prof Shaun Treweek

Thematic series
Stepped wedge randomized controlled trials
Edited by Prof David Torgerson

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Announcing In Review - now available for Trials

Trials has launched In Review, a new option that provides authors with on-demand information on the status of their manuscript, enables them to share their work with funders and their research community, and allows their colleagues to comment and collaborate - all whilst their manuscript is under review. Full details here.

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Aims and scope

Trials encompasses all aspects of the performance and findings of randomized controlled trials in health. We publish articles on general trial methodology and research into trial processes, as well as study protocols and statistical analysis plans for randomized controlled trials, commentaries and traditional results papers - regardless of outcome or significance of findings.

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Peer review mentoring

The Editors endorse peer review mentoring of early career researchers. Find out more here

Thank you to our peer reviewers

The editors and staff of Trials would like to warmly thank our peer reviewers whose comments have helped to shape the journal.

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Call for papers: Big data for randomized trials

We are pleased to announce that Trials is accepting submissions for a new thematic series on using big data for randomized trials. Edited by Dr Lars Hemkens (University Hospital Basel, Switzerland), this series will consider articles that report on what is currently known about using big data or routinely collected data (such as electronic health records, registries or administrative databases) for randomized trials.

Call for papers: The future of pragmatic trials

We are pleased to announce that Trials is accepting submissions for a new thematic series on the future of pragmatic trials. Edited by Professor Marion Campbell (University of Aberdeen, UK) and Professor Sandra Eldridge (Queen Mary University of London, UK), this series will consider articles that report on any topic relevant to the role, definition and use of the pragmatic trial design.

Jeremy Grimshaw

About the Editors

Jeremy Grimshaw, Editor-in-Chief

Jeremy Grimshaw is a Senior Scientist in the Clinical Epidemiology Program at the Ottawa Health Research Institute and Professor of Medicine, University of Ottawa. He holds a Tier 1 Canadian Research Chair in health knowledge transfer and uptake. Professor Grimshaw’s research interests are in implementation and knowledge translation, quality improvement, complex interventions, systematic reviews, cluster randomized trials, quasi-experimental studies and behavioral theories (and their application to professional behavior).

New Content Item

Tianjing Li, Editor-in-Chief

Tianjing Li is an Associate Professor in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health (JHBSPH). Dr Li was trained as a physician and subsequently earned her PhD in Epidemiology (Clinical Trials concentration) and MHS in Biostatistics from JHBSPH. The primary goal of Dr Li's research is to develop, evaluate, and disseminate efficient methods for comparing healthcare interventions and to provide trustworthy evidence for decision making. Her core research interests include methodologies for randomized controlled trials, systematic reviews, network meta-analysis, comparative effectiveness research, and patient-centered outcomes research. Dr Li serves as the Associate Director for Cochrane United States and the Director for Research for Cochrane Eyes and Vision US Project.

Shaun Treweek

Shaun Treweek, Editor-in-Chief

Shaun is Professor of Health Services Research in the Health Services Research Unit at the University of Aberdeen, UK.  Prof Treweek’s research interests are mainly in efficient trial design, particularly pragmatic trial design, improved recruitment and retention interventions for trials, the design of studies to generate trial process evidence and the effective presentation of research evidence.  He is leading an initiative called Trial Forge ( that aims to be more systematic about how we generate and use research evidence in making trial design, conduct, analysis and reporting decisions. 

Celebrating Trials' 10th anniversary

2016 marked the 10th anniversary of Trials and to coincide with publication of our 3000th article, we put together a page to celebrate the great milestones of the journal, including a timeline, opinions from those in the field, links to our most popular articles, and more.


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