Evaluating complex interventions: What are appropriate methods?

In this CEDIL Methods Brief, we identify four types of complex development interventions: long causal chain interventions, multicomponent interventions, portfolio interventions, and system-level interventions. These interventions are characterised by multiple activities, multiple outcomes, multiple components, a high level of interconnectedness, and non-linear outcomes. We identify a number of approaches that support the evaluation of different types of complex interventions.