The components of complex interventions are frequently discussed, invoked and examined in theory and research but seldom defined. This leads to theoretical and ontological ambiguities, lack of methodological transparency, and potentially, resistance to the wider movement towards complex...

Randomized trials of complex public health interventions generally aim to identify what works, accrediting specific intervention ‘products’ as effective. This approach often fails to give sufficient consideration to how intervention components interact with each other and with local context....