Making Statistics on Human Trafficking Work

ABSTRACT

An overview is given of available international statistics on victims of human trafficking from official records (UNODC and Eurostat), survey research (Walk Free) and Multiple Systems Estimation. It is argued that official figures should be seen as output indicators of law enforcement and other involved institutions rather than as indicators of prevalence. The author welcomes the Global Slavery Index of Walk Free and Multiple Systems Estimations applied to multi-source datasets on trafficking victims as more credible sources of information on true prevalence. These two data sources should be consolidated into a comprehensive analysis to enhance the overall impact of available datasets on policymaking.

KEYWORDS:

• Official figures
• survey-based estimates
• multiple systems estimation
• consolidation of data
• comprehensive analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

¹ The 2018 UNODC report provided several examples of sudden increases in the number of detected victims in a country after the introduction of new institutions or anti-trafficking policies (United Nations Office on Drugs and Crime UNODC, 2018).

² The IOM database on repatriated victims is used for the estimation of victims of trafficking for sexual exploitation.

³ This is not to say that there is no need for extended survey research on human trafficking. Considering the concentration of victimization among hard-to-find population segments, such as illegal migrants in many western countries, bespoke surveys applying innovative sampling strategies are urgently called for (Zhang et al., 2014).

⁴ Illustrative for the lack of official recognition is the absence of references to the GSI indices or the Government Responses index in the country reports of GRETA and the TIP reports of the USA State Department.

⁵ Many governments consider crime rates as politically sensitive information (van Dijk, 2008). For this reason, they are reluctant to acknowledge indicators that have been produced outside their administrative control.

⁶ Given the limited sizes of the samples in the Gallup World Poll (usually 1.000 per country) changes between two sweeps might not be statistically significant. The repeat of the GWP will permit combining samples from two or more years and averaging the victimization rates.

⁷ A pertinent example from the United Kingdom are minors working as drug couriers for so-called “county lines” in different parts of the country. By now, these minors make up a significant part of identified victims of trafficking, but they have largely been missed in the MSE study that used data from 2013 since few such victims had been recorded at the time.