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Table 1 Example research questions and methods for evaluating each process

From: Process evaluations for cluster-randomised trials of complex interventions: a proposed framework for design and reporting

Domain Example research questions Research methods that could be applied Probable best stage of study to collect data
Recruitment of clusters How are clusters sampled and recruited? Documentation of recruitment process by research team. Pre-intervention
Who agrees to participate? Quantitative comparison of recruited and nonrecruited clusters.
Why do clusters agree to participate (or not) Qualitative analysis of interviews with cluster gatekeepers or members.
Delivery to clusters What intervention is actually delivered for each cluster? Is it the one intended by the researchers? Qualitative analysis of observational, interview and documentary data relating to the cluster-level intervention. Pre-intervention and early intervention
Response of clusters How is the intervention adopted by clusters? Quantitative data measuring cluster members’ perceptions of the intervention and uptake of trial components. Qualitative analysis of observational, interview and documentary data about how clusters adopt the intervention. Pre-intervention and early intervention
Recruitment and reach in individuals Who actually receives the intervention in each setting? Are they representative? Measurement of receipt in target population. Quantitative comparison of those receiving vs. not receiving the intervention. During intervention
Why do clusters achieve the pattern of reach they do? Do they introduce selection bias? Qualitative analysis of observational, interview and documentary data about how clusters achieve reach.
Delivery to individuals What intervention is actually delivered for each cluster? Qualitative analysis of observational, interview and documentary data about what intervention is delivered and why. During intervention
Is the delivered intervention the one intended by the researchers? Measurement of intervention fidelity across its components.
Response of individuals How does the target population respond? Qualitative analysis of observational and interview data about target population’s experience of and response to the intervention. During intervention and post-intervention
Maintenance How and why are these processes sustained over time (or not)? Any of the above, but probably focused on processes identified as critical, or as likely to be difficult to sustain. During intervention and post-intervention
Unintended consequences Are there unintended changes in processes and outcomes, both related to the trial intervention and unrelated care? Qualitative analysis of observational and interview data for identification. Quantitative data collection for potential unintended consequences during the trial, or use of routine datasets. Intervention and post-intervention
Theory What theory has been used to develop the intervention? Quantitative process data analysis can assess whether predicted relationships and sequences of change happened during implementation. Post-intervention
Context What is the wider context in which the trial is being conducted? Qualitative data collection from policy documents or interviews. Pre-intervention and early intervention
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