What is Process-Tracing Actually Tracing? The Three Variants of Process Tracing Methods and Their Uses and Limitations
35 Pages Posted: 1 Aug 2011 Last revised: 21 Aug 2011
Date Written: 2011
Despite the widespread use of process tracing (PT) in empirical research and an increasing body of methodological literature on PT and causal mechanisms, there has been little progression in the development of PT methodology. This confusion is partly the product of defining PT as a single research method. We argue that a lot of the murkiness about what PT actually is and how it should be used in practice can be cleared up by differentiating PT methodology into three distinct variants. In our opinion there are three clearly identifiable variants of PT: 1) theory-testing PT that deduces a theory from the existing literature and then tests whether there is evidence that a hypothesized causal mechanism is actually present in a given case; 2) theory-building PT that has the ambition is to build a theoretical explanation from the empirical evidence of a particular case, resulting in a systematic mechanism being theorized; and 3) explaining outcome PT, which is a case-centric method that attempts to craft a minimally sufficient explanation of an outcome using an eclectic combination of theoretical mechanisms and/or non-systematic, case-specific mechanisms.
What differentiates the three variants is: whether they aim to build or test theorized causal mechanisms their understanding of the generality of causal mechanisms (from systematic mechanisms expected to be present in a population to case-specific mechanisms); and the types of inferences being made, where theory-testing/building variants are only able to make inferences about the presence/absence of a mechanism in a single case, whereas explaining outcome PT enables inferences about the sufficiency of the explanation in the single case to be made.
These differences have important methodological implications for research design that are masked when we treat PT as a single method, with the most important being whether the PT study can be nested in a mixed-method design or not.
Keywords: process tracing methods, causal mechanisms, mixed-methods
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