the time between the first and last criminal act represents the duration of the criminal career. Instead of measuring the total duration, studies such as this – which concern a limited time period – consider the length of the residual career. This shows for how long the individual can be expected to be criminally active, assuming the individual is so at present.

Duration presupposes recidivism. If not, the duration would be 0. Offenders exhibiting a criminal career with a duration of 0 are in fact a very significant group. The characteristics of this group will therefore be examined separately when compared to the repeat offenders.

Whereas measurement of duration indicates how long an individual is criminally active, recidivism indicates how many have returned to commit new offenses. Information concerning recidivism hence complements that about duration. Both are therefore included in the current chapter in order to render a better comparison to traditional recidivism studies.

Both the common crime statistics and the measurements of prevalence show that crime decreases very quickly with age, and that there are very few active offenders among elderly subjects. One of the questions to be examined here is whether this reflects a career's duration, or whether it is crime frequency that primarily influences the age distribution. The duration of the career will also be studied in relation to gender and employment status.

Measurement of Duration

Relatively few studies of the duration of the career exist. This is probably due to data limitations and difficulties.