Broadening the range of designs and methods for impact evaluations

Impact Evaluation (IE) aims to demonstrate that development programmes lead to development results, that the intervention as cause has an effect. Accountability for expenditure and development results is central to IE, but at the same time as policy makers often wish to replicate, generalise and scale up, they also need to accumulate lessons for the future. Explanatory analysis, by answering the ‘hows’ and ‘whys’ of programme effectiveness, is central to policy learning.

The study considers existing IE practice, reviews methodological literatures and assesses how state-of-the art evaluation designs and methods might be applied given contemporary development programmes.

The study goes on to conclude that most development interventions are ‘contributory causes’. They ‘work’ as part of a causal package in combination with other ‘helping factors’ such as stakeholder behaviour, related programmes and policies, institutional capacities, cultural factors or socio-economic trends. Designs and methods for IE need to be able to unpick these causal packages.