Addressing attribution of cause and effect in small n impact evaluations: Towards an integrated framework

This paper from the International Initiative for Impact Evaluation (3ie) analyses the various approaches that are available for small n impact evaluations.

It comes to a conclusion that a number of them share a methodological core that could be used as a consensus.


  • Defining small n
  • Evaluation approaches for small n impact analysis 
  • Group I approaches
  • Realist Evaluation
  • General Elimination Methodology (GEM) – aka The Modus Operandi Method
  • Process Tracing
  • Contribution Analysis
  • Group II approaches
  • Most Significant Change (MSC)
  • Success Case Method (SCM)
  • Outcome Mapping (OM)
  • Method for Impact Assessment of Programs and Projects (MAPP)
  • Small n attribution
  • Tackling bias
  • Respondent biases
  • Evaluator biases
  • Addressing bias
  • Towards an integrated framework: common steps for causal inference in small n cases
  • The attribution question(s)
  • Setting out a programme’s Theory of Change
  • Evaluation plan for data collection and analysis
  • Identifying alternative causal hypotheses
  • Verifying the causal chain


White, H., & Phillips , D. International Initiative for Impact Evaluation, (2012). Addressing attribution of cause and effect in small n impact evaluations: towards an integrated framework (Working Paper 15). Retrieved from website:

Originally sourced from Monitoring and Evaluation NEWS