Introduction

The goal of this chapter is to understand which combinations of explanatory conditions account for the qualitative differences between various pathways of human trafficking. The chapter is organized into three parts. First, set-theoretic MMR is described and justified as an appropriate analytical strategy. Set-theoretic MMR is a relatively new methodological approach that combines qualitative comparative analysis (QCA) at the comparative level and process tracing at the within-case level (Schneider and Rohlfing, 2013a). Second, the data and analytical steps of the fsQCA are briefly detailed to prepare the reader to understand the results of the human trafficking pathways. A more in-depth explanation of the fsQCA analysis, including calibration and tests of necessity, can be found in the Appendix. Finally, the third part presents and discusses the results of the fsQCA pathways before concluding with the process tracing that will be explored through the country-specific case studies in the proceeding chapters.

Set-theoretic multi-method research

Set-theoretic MMR combines QCA at the comparative level and process tracing at the within-case level (Schneider and Rohlfing, 2013a). The two methods of process tracing and QCA are compatible when used together for several reasons. First, QCA is well matched with cross-national research as it blends the methods of comparative sociology and case-oriented research. Due to this QCA is complemented by comparative historical methodology like process tracing which has often focused on cross-case comparisons (Mahoney and Rueschemeyer, 2003; Rihoux, 2006; Skaaning, 2011). Second, both comparative historical analysis and QCA require high case knowledge and emphasize that the researcher move between theory and data when selecting cases and specifying variables (Ragin, 2000; Schneider and Wagemann, 2010; Lange, 2012; Lee, 2013). Finally, process tracing and QCA both allow for assessing causal complexity and causal conjunction, especially in cases of equifinality (Tomini, 2018). Conjunctural causation refers to understanding the ways multiple causal mechanisms link together to explain the outcome while equifinality recognizes that there may be multiple pathways to the same outcome. In the next section, process tracing as a method is detailed briefly before discussing fsQCA.