When to use it
Use it to design evaluation and identify evidence that could disprove the intended mechanism.
When to be cautious
A neat chain of boxes is not proof of causation or a substitute for a credible comparison.
Apply it
- State the intended outcome and the people affected.
- Describe the proposed mechanism, external conditions and alternative explanations.
- Choose observations that test the mechanism and support decisions.
An example in practice
Training attendance rises but service errors do not fall. Investigate whether staff had opportunities and support to apply the skills.
Source & credit
Evaluation practice has multiple research traditions. This is an authoritative later guide, not a claim of sole invention.
This explanation and example are independently written. The source is a reading reference; linking it does not grant permission to reuse its text, figures or assessments.