This article has a correction

Please see: J Epidemiol Community Health 2014;68:590

J Epidemiol Community Health 68:101-102 doi:10.1136/jech-2013-202869
  • Editorial

Process evaluation in complex public health intervention studies: the need for guidance

Open Access
  1. Janis Baird3
  1. 1DECIPHer UKCRC Public Health Research Centre of Excellence, School of Social Sciences, Cardiff University, Cardiff, UK
  2. 2DECIPHer UKCRC Public Health Research Centre of Excellence, School of Social and Community Medicine, University of Bristol, Bristol, UK
  3. 3MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
  4. 4Centre of Excellence in Intervention and Prevention Science, Melbourne, VIC Australia
  5. 5Social Science Research Unit, Institute of Education, University of London, London, UK
  6. 6The Primary Care Unit, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
  7. 7Cardiff University Schools of Social Sciences and Medicine, Cardiff, UK
  8. 8DECIPHer UKCRC Public Health Research Centre of Excellence, Cardiff, UK
  9. 9School of Health and Related Research, University of Sheffield, Sheffield, UK
  10. 10MRC Social and Public Health Sciences Unit, GLASGOW, UK
  1. Correspondence to Dr Graham Moore, DECIPHer UKCRC Public Health Research Centre of Excellence, School of Social Sciences, Cardiff University, Cardiff cf103bd, UK; MooreG{at}
  • Received 15 May 2013
  • Revised 30 July 2013
  • Accepted 13 August 2013
  • Published Online First 10 September 2013

Why is process evaluation needed in complex public health intervention research?

Public health interventions aim to improve the health of populations or at-risk subgroups. Problems targeted by such interventions, such as diet and smoking, involve complex multifactorial aetiology. Interventions will often aim to address more than one cause simultaneously, targeting factors at multiple levels (eg, individual, interpersonal, organisational), and comprising several components which interact to affect more than one outcome.1 They will often be delivered in systems which respond in unpredictable ways to the new intervention.2 Recognition is growing that evaluations need to understand this complexity if they are to inform future intervention development, or efforts to apply the same intervention in another setting or population.1 Achieving this will require evaluators to move beyond a ‘does it work?’ focus, towards combining outcomes and process evaluation. There is no such thing as a typical process evaluation, with the term applied to studies which range from a few simple quantitative items on satisfaction, to complex mixed-method studies exploring issues such as the process of implementation, or contextual influences on implementation and outcomes. As recognised within MRC guidance for evaluating complex interventions, process evaluation may be used to ‘assess fidelity and quality of implementation, clarify causal mechanisms and identify contextual factors associated with variation in outcomes’.1 This paper briefly discusses each of these core aims for process evaluation, before describing current Medical Research Council (MRC) Population Health Sciences Research Network (PHSRN) funded work to develop guidance for process evaluations of complex public health interventions.

Intervention implementation

An important role for process evaluations is to examine the quantity and quality of what was actually implemented in practice, and why. This may inform implementation of similar interventions elsewhere, and facilitate interpretation of intervention outcomes. While notions of standardisation are central to implementation assessment, the nature of …