[USA] The Impact of Gang Formation on Local Patterns of Crime
Journal of Research in Crime and Delinquency, Vol. 44, No. 2, 208-237 (2007)
http://jrc.sagepub.com/cgi/content/abstract/44/2/208
George Tita ; Greg Ridgeway
"Research has demonstrated that even after controlling for individual level attributes, individuals who join gangs commit more crimes than do nongang members. Furthermore, the offending level of gang members is higher when they report being active members of the gang. Therefore, gang membership clearly facilitates offending above and beyond individual level characteristics. But what impact does the onset of gangs have on aggregate crime patterns?"