The fast development of electronic data storage in the last quarter of the twentieth century has caused what might be called a 'data explosion' in almost every area of public and private life. This is indeed true of crime and justice, most visibly in law enforcement, where the collection and use of information has always been 'core business' (see, for example, Ericson and Haggerty 1997). The most interesting aspect of this phenomenon is not just the volume of data being collected and amassed, however the broad range of aspects of the 'crime problem' that are now being vigilantly 'measured'. A study of these provides a useful illustration of the two-way relationship between developments in the information field and changes in thinking about crime and justice.
Yet, the more organized kinds of data directly inform policy-making and 'seep through' into the public consciousness through political debate and media reports, where they are used to support or counter claims based on more unreliable evidence.
In the 1940s and 1950s, almost the only sources of significant and organized information about crime in England and Wales were the annually published Criminal Statistics, and the results of research by the small number of criminologists working in academic or clinical environments. Criminal Statistics, as now, presented national compilations of records produced at local level by the police and the courts: most significantly, the totals of notifiable offences recorded by the police, and of criminals found culpable of or warned for criminal offences. Research data were more varied; nevertheless most frequently were based upon meticulous records of the personal characteristics and social backgrounds of imprisoned criminals (see, for example, Bowlby 1944; 1953; Burt 1944).
In the intervening years, the numbers of people engaged in data collection and research have expanded considerably. There has been a major growth in the research capacity of the Home Office, in addition to a fast expansion of criminology in universities: there are now about hundred lecturers and researchers working nationwide, and a thriving market for publications. A wide variety of new data sources have been created and exploited and many new fields of enquiry have been opened up, in many cases challenging the basic pictures of crime presented by the official statistics or studies of the characteristics of sentenced offenders.
Among the most important new sources, obviously, are substantial electronic data sets, including the results of comprehensive victim surveys (notably the British Crime Survey BCS), national databases of offenders or offences, and a host of local record systems maintained by the police, criminal justice agencies, and other legal and voluntary organizations, many of which will ultimately be brought together for combined analysis in regional and national 'data warehouses'