"Law enforcement agencies are the best source of information about the type and level of gang crime or gang incidents in a community. All law enforcement agencies collect information about crimes that occur in their communities, usually by police beat or district, as well as for the community as a whole. They also collect information about the people arrested for committing crimes and some information about the victims of crime. Some agencies have begun segregating gang crime from non-gang crime. Even if the law enforcement agency is not identifying gang incidents separately, they are likely gathering intelligence -- often from encounters with gang members themselves -- about the gangs that are present in the community, their members, their strength, and their activities.

"Monthly or seasonal variations in crime also should be considered when collecting the data. For example, gang activity may be seasonal-some months may be 'heavier' than others for gang crime. Day of the week and time of day, as well as location(s) of gang crime also are important factors in assessing local gang crime problems.

"Finally, information about the victims of gang crime should be collected. If possible, data should be collected about their age, gender, race, gang affiliation (if any), and involvement in the crime that was committed. The purpose of this information is to determine if victims are other gang members, rival gang members, and the age, race, and gender of the victim. If victim information is not available from law enforcement, it may be obtained through focus groups, from individual interviews with youth, community surveys, or, in some communities, from hospital emergency rooms.

"Crime data should be collected for the last three calendar years and by the smallest geographic area-census tract, police beat or reporting district, or community area."