Table 6

Support for proposition 2 - complex interventions evolve and change
Findings in support of proposition Evidence source
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Trial 7
1. Standardising complex interventions is challenging, because interventions may frequently be inseparable from contexts and contexts themselves are rarely static. ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓
2. Researchers generally have a theory of how the intervention and trial should work but this is not always made explicit. Theories of how an intervention actually should or does work can also change as contextual information becomes more apparent. ✓✓ ✓✓ ✓✓ ✓✓ ✓✓ ✓✓
3. Relationships between people involved in complex intervention trials evolve and change thereby changing the intervention.
4. Complex intervention trials have a knock-on effect on the practice context, which may then lead to further evolution and change in the intervention. ✓✓ ✓✓ ✓✓

✓ = some evidence (one instance); ✓✓ = strong evidence (more than one instance); no check/tick = no specific evidence.

Wells et al.

Wells et al. Trials 2012 13:95   doi:10.1186/1745-6215-13-95

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