Do I need a process evaluation?

Conducting process evaluations, including alongside randomised controlled trials, requires additional resources but they enable researchers to understand how complex interventions work and how they might best work in the future. This maximises the number and quality of findings from a study, and reduces the need for (and costs of) additional research.

A process evaluation can help you understand:

  • How an intervention worked (or why it did not work)
  • Intervention fidelity: was the intervention delivered as intended? Understanding exactly what intervention was delivered is the basis for interpreting other aspects of a trial such as acceptability, participant response and outcomes
  • Implementation issues e.g. how practitioners adopted new ways of working (this is especially important for feasibility and effectiveness trials)
  • Why an intervention worked in some settings, or for some groups, but not others
  • How the context of an intervention affected how it was delivered and received
  • Whether theory in your field needs revising – process evaluations test and refine theory (intervention theory explains the mechanisms or ‘cogs and wheels’ of how an intervention works and how it brings about change)
  • Whether there were redundant or harmful components of an intervention
  • How an intervention should be refined between the feasibility and definitive trial stages
  • How an intervention should be implemented in wider roll-out