What is Process evaluation?
Process evaluation assesses how a behavior change intervention was implemented, received, and experienced, as opposed to outcome evaluation which measures whether it produced the desired behavior change.
How it works
Process evaluation answers: Was the intervention delivered as planned? Did participants engage? What contextual factors influenced delivery? What unexpected adaptations occurred? This information is essential for interpreting outcome results: if an intervention fails, process evaluation reveals whether it was a theory problem or an implementation problem. The MRC framework recommends process evaluation alongside outcome evaluation for all complex interventions.
Applied example
A workplace stress reduction program shows no effect in the outcome evaluation. Process evaluation reveals that only 30% of employees attended sessions (low reach), sessions were shortened from 60 to 30 minutes (low fidelity), and managers discouraged attendance during busy periods (contextual barrier). The program theory may be sound; the implementation was not.
Why it matters
Process evaluation is indispensable because it explains why interventions succeed or fail, enabling improvement rather than just pass/fail verdicts.
