Statistics: Historical Trends in Western Society

Since the incidence of crime is largely unpredictable—like an earthquake—it can be measured only after it has already taken place. The measurement of crime, therefore, is subject to all the errors that indirect measurements entails. Attempts to measure crime omit some cases, record some that are not criminal, and incorrectly classify others. All attempts to measure crime reflect not simply the underlying incidence of criminal behavior but also any biases inherent in the measurement process itself.

Three common sources of information about crime include governmental organizations (the police, the courts, and correctional departments), individual researchers in contact with offenders (self-report studies), and survey organizations such as the U.S. Census Bureau, which collects victimization data. Most of what is known about crime is derived from at least one of these sources. Each assesses a distinct facet of crime and experiences distinct problems. Crime data issued by the courts and police have been a major source of information regarding criminality, especially before the modern era, but one must be aware of biases in data.

Police departments in particular are subject to many pressures that distort the crime picture they present. Some large departments are more effective in solving criminal cases than others, as a result of professional leadership, high morale, careful recruitment, or strong training programs. At the same time small departments in towns under ten thousand where neighborliness is the rule often have more accurate statistics regarding offenders, whether juveniles or adults; whites or blacks; or males or females, because thanks to cooperative attitudes among local people, they are able to solve a much larger portion of their minor crimes than departments in large cities. In towns with populations under 10,000 for example, 27.6 percent of motor vehicle thefts were cleared by arrests in 1998, but in cities with populations of one million or over, only 8.8 percent of these offenses were cleared.

This differential carries important implications for crime data on such problems as juvenile delinquency. If auto thefts are not cleared by arrests, the police have no basis for knowing what portion was committed by juveniles—normally about 8 percent in cities greater than 1 million. Since motor vehicle thefts are solved in small towns at rates substantially higher than in major cities, demographic data on auto thieves in small towns is more accurate than in large cities. In comparing the delinquency problem in major cities and small towns one must keep this difference in mind.

Inaccurate population estimates and subsequent distortions in crime rates also pose problems. It is very difficult to estimate population levels of cities and towns during serious social turmoil. During the Civil War large numbers of citizens were transplanted, thus making it difficult to gauge population size. For example, the U.S. Census Bureau conducted a census in Massachusetts at the beginning of the 1860s, and the state itself carried out another in 1865. But with a rapid influx of immigrants from Ireland and disturbances accompanying the Civil War, many lower-class people were not counted. Although the arrest figures were apparently accurate, arrests per 10,000 (as computed in those days) were inflated as a result of an under-estimate in the overall count. Crime data must be presented as rates per unit of population to enable comparisons among different sized cities, but if the population is inaccurately counted, crime rates will be skewed and comparisons unwise.

A different kind of problem plagues comparisons of criminality during different periods in the history of a city. It is common knowledge that policing takes several different forms or styles and that these distinctive styles operate at different levels of effectiveness. James Q. Wilson (1968) has identified three common patterns of operation among police departments. The service department tends to be small, close to the community, and informal, with few authority levels and little specialization. The watchman department tends to be larger, serving ethnically diverse cities in a balanced, unaggressive fashion. It seeks to avoid interethnic conflict and attempts above all to maintain stability in the community. The legalistic department puts more emphasis upon careful recruitment, sound training, and careful, dispassionate administration of the law (Wilson, chapters 6–8). This typology, though often criticized, has been widely used in police research. As a police department grows, if often becomes more formal and less approachable (Ferdinand, 1976). And as it evolves from a service to a legalistic or watchman pattern, its overall effectiveness and clearance rate decline. Such changes can have a sharp impact on complaints known to the police and on estimates of delinquency. Changes in city crime rates over several decades may well reflect such organizational changes. Long-term fluctuations in violent crime in Boston and Salem, cited below, probably also reflect such changes, that is, shifts in police style. Citizen cooperation, complaints brought to the police, and clearance rates all gradually decline as the community and its police department mature.

Court data must also be used with an eye to the peculiarities of a changing court system. Different criminal courts normally have jurisdiction over different segments of the criminal spectrum. City, state, and federal courts each despose of a distinctive blend of crime, and no single court can provide an accurate estimate of crime in a city. Each has its own distinctive jurisdiction, but two courts at different levels in the same system provide a more complete picture. Each court nevertheless follows different policies in prosecuting crime, and their jurisdictions do not overlap precisely. It is not always feasible, therefore, to assemble an accurate estimate of crime in the community from the activities of two or more related courts at different levels in the same system.

Pitfalls also await those who would compare the activities of a single court over time. For example, the same court may change its name and jurisdiction with the result that historians might inadvertently compare a lower court with a higher court. The Boston Municipal Court was established in 1800, but in 1859 it was renamed the Superior Court of Suffolk County. The Boston Police Court was founded in 1822, and in 1859 it was renamed the Municipal Court of Boston! A comparison of the Municipal Court in 1850 with the Municipal Court in 1870 would be inappropriate, because it would compare a lower court with a higher one. Despite these problems, the courts and the police are very useful sources of information regarding the incidence and distribution of crime, and for historical periods they offer virtually the only systematic data available. It is wise, nevertheless, to be aware of their weaknesses.