The study identified what are generally known as “strategic offenses.” It estimated how large a proportion of offenses were committed by individuals engaged upon different types of criminal careers and in which offense categories. It also examined variations between different birth cohorts to see whether the results were stable over time. Approximately 24 percent of persons born in Sweden in 1960 had been convicted of an offense; the proportion increased to 37 percent for men, while for women it was 10 percent. Strategic offenses included vehicle theft, robbery and theft. More than one-quarter (27 percent) of those receiving their first conviction in connection with a vehicle theft would subsequently be among the small group responsible for 50 percent of all offenses committed. The risk of becoming a chronic offender was 19 percent for those whose first conviction was for robbery and 16 percent for those whose first conviction was for theft. Findings remained stable over time.