Source of complexity | Difficulties in rating estimates of the effect of interventions |
Multiple components |
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Flexibility or tailoring or non-standardisation of implementation |
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Long causal pathways |
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Effects are contingent on recipients’ and providers’ agency |
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Multiple outcomes |
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Effects at different levels, for example, individual and population levels |
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Moderating effects of context |
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GRADE, Grading of Recommendations Assessment, Development and Evaluation; RCT, randomised controlled trial.