The United States Government Accountability Office (GAO) produced a study in July 2006 questioning the manner in which the State Department calculated its human trafficking figure. The GAO stated that estimates are ” questionable” . In its Results in Brief section, the report states ” The accuracy of the estimates is in doubt because of methodological weaknesses, gaps in data, and numerical discrepancies.”
Source: United States Government Accountability Office, “Human Trafficking: Better Data, Strategy, and Reporting Needed to Enhance U.S. Antitfafficking Effort Aboard,” July 2006.