Despite the magnitude of these figures, few quantitative studies have been done in this area. This is mainly because acquiring the relevant data is difficult and its collection process is not homogeneous across countries. Uniform data collection is largely affected by government effectiveness in identifying relevant actors (both victims and traffickers), as they belong to the “hidden population” (Heckathorn, 1997). In addition, given how politicized the topic is, identification efforts may be directed towards specific human trafficking segments, above all sexual exploitation (Tyldum and Brunovskis, 2005). Therefore, the scarce quantitative research on human trafficking bases its analysis on self-constructed estimations and proxies or on surveys implemented for specific case studies. Despite the importance of these approaches, they limit comparability and impede identification of relevant factors driving human trafficking. Recent attempts to empirically address the subject are a response to the increased attention human trafficking has received internationally.