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Professor Sandra Eldridge


Professor of Biostatistics; Director, Pragmatic Clinical Trials Unit

Telephone: 020 7882 2519


Sandra gained a degree in Mathematics from Oxford University in 1979. She then spent two years teaching mathematics in secondary schools, first in Nigeria with Voluntary Service Overseas, then in the UK. In 1982 she completed an MSc in Medical Demography at the London School of Hygiene and Tropical Medicine where she worked for several years before moving to London Metropolitan University (formerly City of London Polytechnic) to teach undergraduate statistics. She joined Queen Mary as a lecturer in medical statistics in 1994, working predominantly in primary care. She developed an interest in cluster randomised trials and completed a doctorate focusing on these trials in 2005.

From 2007 she has been joint lead (with Chris Griffiths) of the Centre for Primary Care and Public Health. She is also director of the Pragmatic Clinical Trials Unit housed within the Centre and joint lead for the Barts and The London arm of the Research Design Service. She was instrumental in setting up the Royal Statistical Society Primary Health Care Study Group in 2002. Sandra is a member of the Society for Academic Primary Care Executive, sits on various NIHR funding panels and currently leads an international group of researchers developing reporting guidelines for pilot and feasibility studies.


Sandra's main research interests are cluster randomised trials and complex interventions particularly in primary care. She has published a number of key papers on cluster randomised trials. In addition to her methodological research she has responsibility for the statistical design and analysis aspects of a large number of collaborative research projects mostly concerned with the management of chronic conditions; many of these projects involve cluster randomised trials.


Topics for PhD supervision:

Methods in pragmatic trials especially cluster randomised trials, methods for complex interventions



Eldridge S, Kerry S, Torgerson DJ. Bias in identifying and recruiting participants in cluster randomised trials: what can be done? BMJ. 2009 Oct 9;339.

Eldridge S, Ashby D, Bennett C, Wakelin M, Feder G. Internal and external validity of cluster randomised trials: systematic review of recent trials. BMJ 2008; 336(7649):876-880.
Eldridge SM, Ashby D, Kerry S. Sample size calculations for cluster randomized trials: effect of coefficient of variation of cluster size and analysis method. Int. J. Epidemiol. 2006 Oct;35(5):1292-300

Eldridge S, Spencer A, Cryer C, Parsons S, Underwood M, Feder G. Modelling a complex intervention is an important precursor to trial design: lessons from studying an intervention to reduce falls-related injuries in older people. J Health Serv.Res Policy 2005;10:133-142.

Eldridge SM. Ashby D. Feder GS. Informed patient consent to participation in cluster randomised trials: an empirical exploration of trials in primary care. Clinical Trials 2005; 2: 91-98

Eldridge SM, Ashby Barbanel D, Eldridge S, Griffiths C. Can a self-management programme delivered by a community pharmacist improve asthma control? A randomised trial. Thorax 2003;58:851-4.

View all Sandra Eldridge's Research Publications at:

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