The gang estimates presented in the 2011 National Gang Threat Assessment (NGTA) represent the collection of data provided by the National Drug Intelligence Center (NDIC) through the National Drug Threat Survey, Bureau of Prisons, State Correctional Facilities, and National Gang Intelligence Center (NGIC) law enforcement partners. An overview of how these numbers were collected is described within the Scope and Methodology Section of the NGTA. The estimates were provided on a voluntary basis and may include estimates of gang members as well as gang associates. Likewise, these estimates may not capture gang membership in jurisdictions that may have underreported or that declined to report. Based on these estimates, geospatial maps were prepared to visually display the reporting jurisdictions.