The Bureau of Crime Statistics and Research researches crime causes and the effectiveness of criminal justice policy. The bureau aggregates data from the records of criminal justice agencies to provide information relevant to criminal justice planning and policy implementation. In addition to relying on official property crime statistics to develop policy in this area, the bureau also conducts statistical and social surveys, usually when evaluating programs or legislation. To supplement surveys and official data, the bureau uses ethnographic research, which focuses on the characteristics of subcultures or groups. Such a method would be valuable in the study of the lifestyles of offenders involved in persistent burglary. In theory and policy analysis, the bureau focuses on the concept of 'community' as the target of criminal justice planning and policy. The community is idealistically a network of citizens who work with one another and with the criminal justice system to provide a defensive structure that prevents crime in the community. Research should help to determine what kinds of programs are most effective in helping communities meet their safety needs.