ABSTRACT
This chapter looks at methodological challenges and opportunities in addressing impact when taking the long-term perspective in an evaluation. In particular it discusses how contribution analysis can be adapted to address the challenges faced when looking at interventions over several decades. The basic concepts of generative causality and contributory causes remain, but modifications to the usual steps in contribution analysis are suggested. Given the long time frame involved, at the outset, undertaking a structured evaluability assessment is suggested to determine the focus and scope of the evaluation. The steps then taken in the contribution analysis are: (1) Thoughtfully set out the practical causal questions to be addressed, (2) Develop the long-term timeline of the events related to the intervention, (3) Identify the key pathways to impact, and their timelines, (4) Develop related pathway theories of change, (5) Assess the intended changes that occurred, (6) Identify critical causal issues, (7) Develop causal narratives for the pathways, and (8) Conclude on likely contributions made by the intervention and how they happened.
