LSHTM Week: Process Tracing and Bayesian Updating for Impact Evaluation

Date: Fri, 22 Sep 2017

Time: 11-12pm

Venue: Rose Room (LG6)

Speaker: Barbara Befani

This seminar presents the combination of Process Tracing and Bayesian Updating when aiming to establish causal linkages between interventions and outcomes in single-case evaluations. The method relies on generative causation and is potentially very transparent, which makes it replicable and potentially highly reliable / robust. It can be broken down into four broad steps: formulating a contribution claim (or describing how an intervention, together with other factors, has contributed to an outcome); designing data collection with a focus on identifying “conclusive” pieces of evidence, or pieces of evidence that strongly support or strongly reject that claim; assessing the probative value of the above pieces of evidence in terms of their power to confirm or reject the claim; and sharing the findings (the levels of confidence about a series of claims) with a group of experts or stakeholders as a form of peer review. The practical aspects of the method will be illustrated with a policy influence evaluation conducted in a developing country and with an excel based tool to aid confidence updating.


Barbara Befani is a Research Fellow at the University of Surrey (Sociology, Centre for Research in Social Simulation) and a Research Associate at the University of East Anglia (School of International Development). She has spent the last 6 years researching and developing innovative methods for impact evaluation. She has developed a tool to understand 11 methods in-depth and aid appropriate choice and combination of methods in specific impact evaluations. Barbara has over 10 years of experience in teaching and applying Qualitative Comparative Analysis (QCA) and in the last 4 years has been developing and refining a combination of Process Tracing and Bayesian Updating to evaluate impact in single-case evaluations, that she has taught extensively to various types of audiences and has applied to several cases. She is an active member of the global evaluation community and a former Secretary General of the European Evaluation Society (EES).

Watch this online here