Researchers Use Statistical Method to Challenge Criminological Theories

Police Lineup

Criminologists from the Max Planck Institute for Foreign and International Criminal Law in Freiburg set out to see if there is such a thing as a typical criminal career. By using the judicial criminal record data of the 1970 birth cohorts from the age of 14 to 32, their statistical method showed only 2 percent could be classified as life-course-persistent offenders.

Is there such a thing as a typical criminal career? This was the question addressed by criminologist Volker Grundies from the Max Planck Institute for Foreign and International Criminal Law in Freiburg. This study examined the data of approximately 21,000 men from Baden-Württemberg, who had come into conflict with the law on one or more occasions. The results of his study challenge widely held criminological theories surrounding the development of delinquent behavior in the life of an individual.

In this project, Grundies and his colleagues at the Freiburg-based Institute analyzed the judicial criminal record data of the 1970 birth cohorts from the age of 14 to 32 using a statistical method developed by criminologists Daniel Nagin and K.C. Land. This method assumes that only a certain number of less typical age trajectories of delinquent behavior exist and that every offender can be categorized according to one of them. They did find several such typical age trajectories; however, these did not hold up to critical examination. “These are actually a product of the method itself, as there is an inherent assumption that such age trajectories exist,” explains Grundies.

As it turned out, 87 percent of the group reported a small number of offenses on their criminal record. Another 11 percent were in conflict with the law more frequently. On average, they had committed seven to eight offenses, which were perpetrated predominantly within a defined age range. Only 2 percent could be classified as life-course-persistent offenders. They had maintained an almost consistent criminal record for the entire duration of the period under observation. According to Grundies: “We can conclude from this that most criminal careers only endure in the medium-term.”

“The bottom line is that the recorded criminal careers can be distinguished according to starting age, frequency of recorded offenses and duration, but they are also characterized by their large but evenly distributed diversity of individual trajectories,” reports Grundies. He contends that no typical trajectories can be discerned from this broad spectrum of potential characteristics. Nor did the Freiburg-based researchers find any real distinct groups in their statistical analyses. “Overlaps existed between all the groups, which means that categorization from a criminology perspective is a meaningless and arbitrary exercise,” says Grundies. “We could not even ascertain a general trajectory that varied only in its individual intensity, as predicted by theories that are focused on certain personality traits.”

The researcher himself was very surprised by this result. “At first, I was certainly frustrated, but then I asked myself what the reason for this could be and I suddenly found the result very exciting.” Ultimately, it confirms his personal theory about the cause of criminal careers: an imbalance between the individual and society. “Even if such imbalances are aggregated at a young age, the lack of patterns indicates that, in principle, this imbalance can occur at any age.”