A study by Norwegian researchers found that the older a person was when he arrived in Norway, the less likely he was to engage in criminal activity. Synøve Nygaard Andersen & Torbjørn Skardhamer, Age at Immigration and Crime: Findings for Male Immigrants in Norway 15 (Dec. 2012).
The two researchers, both of whom work for Norway’s statistics agency, examined records of all male immigrants to Norway between the ages of 15 and 50 who resided there with a valid residence permit at any time between 1992 and 2007. Nygaard & Skardhamer at 7. They started with a baseline age of 15 because that is the minimum age of criminal liability in Norway; they stopped at 50 because there is not much crime committed by people over that age. Nygaard & Skardhamer at 8. Importantly, Nygaard & Skardhamer gathered data from police records of all solved crimes—misdemeanors and more serious offenses; those records include the date of commission rather than just the date of conviction which allowed them to more accurately assess whether people within this age range committed crime. Nygaard & Skardhamer at 8.
Immigrants who arrived before turning 15 committed steadily more crime as they neared age 21 after which their incidence of criminal involvement decreased. Nygaard & Skardhamer at 13. It’s not surprising that criminal activity peaked near 21; this tends to be within the age range in which men are most likely to commit crime. At its peak near 21 years old, about 15% of immigrations who arrived prior to turning 15 committed crime. In contrast, individuals who arrived after age 15 committed very little crime for a short period after arrival “before it increased steadily over a period of about 10 years and stabilized at a level close to or slightly below the levels of the previously arrived groups.” Nygaard & Skardhamer at 13. Even at its highest, however, immigrants who arrived after age 15 tended to commit less crime than those who arrived before age 15.
Breaking these age groupings down a bit more, the pair found that “[t]he predicted probability of offending increased from a relatively high level of 10 per cent for those who arrived at age 0, with a peak of 12 per cent for arrival at age 10, and decreased until the end of the observation period at age 50.” Nygaard & Skardhamer at 15. Individuals who arrived at age 20, for example, became most commonly engaged in crime at about age 25 when approximately 6% were engaged in some form of crime.
Between 1992 and 2007, the percentage of Norway’s residents charged with crimes ranged from a low of about 5.5% in 1992 to a high of about 8.5% in 2001, according to data provided by Statistics Norway.