Randomized Controlled Trials: Strengths, Weaknesses and Policy Relevance

The general purpose of this report is to offer input into the ongoing debate on the evaluation and effectiveness of Swedish foreign aid. More specifically, the focus lies on the role of randomised controlled trials (RCTs) in evaluations of the impact of aid-financed activities. The first part looks at how RCTs have been used in research and practice to promote evidence-based development policy. The second part discusses to what extent this tool has so far been used by Swedish aid practitioners and whether there is reason to expand that use, and finally offers some tentative suggestions on how this could be achieved.

Key findings

  • RCTs are, in the right circumstances, a powerful and high-quality method to evaluate impact.
  • RCTs should be one of many tools for monitoring and evaluation used by aid agencies.
  • Using mixed methods (a combination of RCTs and other quantitative and qualitative methods) is often the ideal approach to learn more broadly about the effectiveness of different dimensions of aid-financed interventions.


  • The fact that RCTs have been used very sparsely, if at all, by the Swedish aid community suggests that there is great potential to increase the quality of impact evaluation of projects and programmes financed by Swedish aid.
  • The existing bank of knowledge, in the form of rigorous impact evaluations that have already been carried out, should be used more systematically.
  • Sida should acquire in-house competence to commission RCTs of projects and programmes financed by Sida or its collaborators.
  • Conducting RCTs requires the cooperation of partner countries and implementing units (NGOs or consultancy firms). A fruitful approach may be to support the development of rigorous impact evaluation skills at partner country universities and research centres.

Author: Anders Olofsgård

The report was presented at the following seminar.