This document is part of the ‘Better Evidence in Action’ toolkit.

Process tracing and Bayesian updating is a quali-quantitative methodology that uses probative confidence updating to assess the strength of the evidence for a specified story of change or causal mechanism. We can use the method to investigate outcomes that are already known and to measure impacts at macro and micro levels. Process tracing is applied widely in political science, psychology and history studies. This method can tell us how and why a specific cause produced a particular effect, but it cannot estimate the net effect of an intervention.