Damned Lies and Statistics by Best Joel

Author:Best, Joel
Language: eng
Format: epub
ISBN: 9780520953512
Publisher: University of California Press
Published: 2012-08-29T04:00:00+00:00

COMPARISONS AMONG PLACES

Another standard sort of comparison is geographic; it compares statistics from different places. These might be numbers from places of the same sort—two or more cities, or states, regions, or countries—or they might involve comparisons of different kinds of places, such as rural and urban areas.

Geographic comparison is basic to much social science. Often it is made easy because bureaucracies have responsibility for keeping records within particular geographic jurisdictions, and it is relatively simple to compare those records. Thus, the FBI invites all law enforcement agencies to submit reports on crimes that have come to their attention; most agencies cooperate, and the FBI compiles its reports into its Uniform Crime Reports, calculating crime rates for the various states, counties, and cities.

Such comparisons depend on the different agencies producing comparable statistics. The FBI tries to guarantee this by providing detailed rules for reporting agencies; these rules seek to ensure that all agencies use the same definitions of crimes, as well as similar methods of measurement. Similar definitions and methods should produce numbers that are reasonably comparable—apples and apples.

But when agencies define phenomena in very different ways, or use different methods of collecting statistical information, the resulting numbers cannot be meaningfully compared (recall chapter 3’s discussion of the unreliability of early hate-crime statistics). Another example involves the records some urban police forces keep of “gang-related” homicides. But what makes a homicide gang-related? Police departments have devised very different answers to that question.7 A department may choose to adopt a narrow definition; for example, labeling a homicide as gang-related only if the killer and the victim were known members of rival gangs and if gang rivalry is known to have been the motivation for the killing. In contrast, another police department may favor a broad definition, counting a homicide as “gang-related” if either the killer or the victim was either a gang member or associated with gang members, regardless of the motivation for the crime. The choice of definition makes a big difference. One study found that applying a broad definition identified twice as many gang-related homicides as a narrower definition. Depending upon circumstances, police departments might prefer to adopt either a broad definition (perhaps using the higher number of gang-related homicides to justify budget increases for an expanded antigang unit), or a narrow definition (presenting a lower number of gang-related homicides as evidence that the department is doing an effective job keeping gangs under control). The point is not that one definition is correct and the other is wrong, but rather that it is pointless to compare statistics collected using different definitions—the two definitions count different things, regardless of whether they both claim to be counting “gang-related” homicides.

Geographic comparisons become particularly troublesome when they involve different countries. Differences in language, culture, and social structure make international comparisons tricky, even when they seem straightforward. For example, critics sometimes argue that the United States has far more lawyers than other countries (usually implying that our oversupply of lawyers fosters excessive, senseless litigation).8

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