Process tracing is an increasingly prominent methodology in political science. This approach was first developed in 1979 and was fleshed out comprehensively in George and Bennett’s Case Studies and Theory Development in the Social Sciences (2005). Process tracing centers on dissecting causation through causal mechanisms between the observed variables, primarily in case studies. In essence, the focus of process tracing is on establishing the causal mechanism, by examining the fit of a theory to the intervening causal steps. Theorists using process tracing ask’ how does “X” produce a series of conditions that come together in some way (or do not) to produce “Y”?’ By emphasizing the causal process the leads to certain outcomes, process tracing lends itself to validating theoretical predictions and hypotheses.
Despite often focusing on only a single case, process tracing is a useful tool for testing theories. Researchers must examine a number of histories, archival documents, interview transcripts, and other similar sources pertaining to their specific case in order to determine whether a proposed theoretical hypothesis is evident in the sequence of a case (George and Bennett, 6). Looking at these sources in terms of the sequence and structure of events can serve as evidence that a given stimulus caused a certain response in a case. Process tracing aims to ascertain the causal process linking an independent variable(s) to the outcome of a dependent variable, particularly in small-n studies. This method is particularly useful for looking at deviant cases and determining the specific factors that lead them to diverge from expected trends. While process tracing may not be able to exclude all but one theory in a given case, it can narrow the range of possible explanations and can disprove claims that a single variable is necessary or sufficient to produce an outcome.
Thus, process tracing can be a valuable approach for testing a theory in a research paper or thesis in which a small number of cases are addressed in a comprehensive manner. For example, a researcher studying the ‘democratic peace theory’ could look at a number of cases (or even just a single case) in which both democratic and non-democratic countries did or did not go to war. Then, through process tracing, these cases can be thoroughly researched and analyzed. By looking at the pertinent facts and sequence of events in these cases and applying them against the tenets of the ‘democratic peace theory,’ the relevance of the theory can be construed and other potential explanations can either be proven either inapplicable or potentially significant. In this manner, process tracing can be a useful test of a theory’s viability.
Articles and Books:
Tansey, Oisín. 2007. “Process Tracing and Elite Interviewing: A Case for Non-Probability Sampling.” PS: Political Science & Politics 40(04): 765-772.
Ford, J. Kevin et al. 1989. “Process tracing methods: Contributions, problems, and neglected research questions.” Organizational Behavior and Human Decision Processes 43(1): 75-117.
George, Alexander L. 2005. Case Studies and Theory Development in the Social Sciences. Cambridge, Mass: MIT Press.
Checkel, Jeffrey T. 2008. It’s the Process Stupid! Tracing Causal Mechanisms in European and International Politics. Qualitative Methods in International Relations. New York: Palgrave Macmillan.