Ian Kellar

I work on the part of health research that decides whether a good idea survives contact with a real service.

Most studies can show that an intervention works under test conditions. Far fewer can say why it worked, or what has to be true in a clinic, a ward or a community setting for it to keep working. That gap is my subject. I write about it, I build methods that make the causal claim explicit before a trial is designed, and I work with clinical teams on studies that carry the claim into practice.

What I actually do

Three threads run through the work.

Mechanism before measurement. A trial that measures the wrong thing precisely is still wrong. I develop methods that force a study to state the mechanism it assumes, then design the measurement around that statement. Causal pathway diagrams are the practical version: a diagram that a clinical team can redraw, argue with, and test.

Behaviour change with a theory of the problem. The frameworks I use most (the Theoretical Domains Framework, the Behaviour Change Technique Taxonomy, the Behaviour Change Wheel) are useful precisely because they are classifications rather than explanations. Used carelessly they displace the causal thinking they were meant to support. I have spent several years arguing that point and proposing what to put in their place.

Implementation as a design problem, not a dissemination step. If an intervention only works when a service is already well organised, that is a finding about the intervention, not a failure of the service. I work on studies that treat implementation as part of the intervention.

Current work

I am Professor of Behavioural and Implementation Sciences (Education and Research) in the Department of Interprofessional Healthcare, School of Health and Medical Sciences, at City St George's, University of London, from November 2026. My home initiative there is the Integrated Care Collaborative: integrated health and care systems, workforce capability, person centred practice, co-design, and the Neighbourhood Health Implementation Programme.

Before that I was Professor of Health Psychology at the University of Sheffield (2023 to 2026), Associate Professor and Lecturer at the University of Leeds (2013 to 2023), a Research Associate at the Cambridge Primary Care Unit (2005 to 2012), and a Research Fellow at the University of Brighton (2004 to 2005).

I hold a DPhil in Social Psychology from the University of Sussex (2005, ESRC funded), a BA in Social Psychology from Sussex (2000), and I am a Chartered Psychologist (Health Psychology).

Research portfolio

I am an investigator or co-applicant on programme and project grants across the NIHR, including the Programme Grants for Applied Research scheme, Programme Development Grants, Health and Social Care Delivery Research, and Research for Patient Benefit. Much of that work is in communication and aphasia after stroke, cancer, mental health, musculoskeletal pain, and screening inequalities. I also supervise NIHR fellowships and doctoral students.

I review for NIHR funding committees, including the Programme Grants for Applied Research sub-committee, and I have served on editorial boards for health psychology journals.

Beyond the day job

I am President of the UK Society for Behavioural Medicine (2025 to 2027). I teach systematic review methods, and I build software: learning sites, tools for research teams, and the occasional game. See Software.

How I work

I write plainly and I prefer a plain claim to an impressive one. If a result is uncertain, I say so. If a mechanism is assumed rather than shown, I say that too. Most of the arguments I make about research methods are arguments about honesty under uncertainty, and the writing on this site tries to keep to the same standard.