QUALITATIVE METHODS
14 Process Tracing
Estelle Raimondo
Abstract
Process tracing is a theory-based evaluation approach. Based on the formulation of a process theory-of-change, it collects evidence to ascertain how the intervention unfolded in a single case and whether it plausibly contributed to change in outcomes. Often described as a qualitative method, process tracing can in fact rely on a diversity of qualitative and quantitative methods. Particularly useful to evaluate complex interventions, it addresses the questions of “under what conditions, how, and why” an intervention worked, rather than how much impact it produced.
Keywords: Qualitative methods, processes, theory-based evaluation, process theory-of-change, causal principles, contribution pathways, evidence, fingerprints, Bayesian reasoning
I. What does this approach consist of?
When evaluators conduct Process Tracing (PT), they behave a bit like “detectives”. When applying process tracing, evaluators are interested in explaining, rather than simply describing, change processes. To put it simply, evaluators seek to trace how the activities of actors/entities and their motivation are interlinked to trigger change in the behavior and action of others. Empirically, process tracing is also akin to “detective work” as it consists of assembling a body of evidence (what D. Beach calls ‘fingerprints’) to ascertain how the intervention unfolded in a single case and whether it plausibly contributed to change in outcomes. In slightly more technical terms, process tracing is a theory-based evaluation approach for studying how interventions worked in actual cases (see separate chapter on theory-based evaluation). As such, process tracing belongs to the family of methods that seek to answer the questions of “how, why and under what circumstances” programs and policies work by studying how they play out in the real-world. Visually, process tracing seeks to understand what is going on ‘in-between’ the arrow linking interventions and results, in a typical theory of change. Its comparative advantage over other methods is in fully opening the black box of change processes.
Process tracing is often considered a “qualitative” approach because it tends to rely on qualitative evidence (from interviews, observations, documents, etc.) but, like many other theory-based evaluation approaches, it resists simple classification and is better described as ‘methods agnostic’. It can accommodate and use a range of methods of data collection and analysis, quantitative or qualitative, in seeking to assemble a body of evidence that is robust enough to adjudicate between the process theory of change under scrutiny and alternative explanations. In addition, more recently, some evaluators have mathematically formalized the use of process tracing through the application of Bayes’ theorem (Befani 2021)
At its core, there are two main phases and a few unique features to process tracing that distinguish it from other theory-bas