Criminology

According to Blumstein and Cohen (1986), the term criminal career pertains to the way in which the crime an individual engages in changes according to the development that the individual goes through during their lifetime.  Their research postulated that a small number of offenders commit the majority of crimes and the number of these offenders diminishes over time.  The criminals who do continue to commit crime become known as career criminals.  Research based on the criminal career theory looks carefully at both the frequency and the prevalence of a crime.  For example, an age crime curve may be created which maps the rate of offending against the age of a criminal.

The concept of the criminal career was criticized by Gottfredson and Hirschi (1990) in their theory of criminal propensity. Criminal propensity considers how differences between different people may shape their predisposition to engage in criminal activity.  According to their argument, in an environment where criminal propensity is high, more offences will be committed and offenders will start to commit crimes at an earlier date.  In addition to this, the duration of the criminals career will be longer.

Research conducted under the theory of criminal propensity differs from that performed under the theory of the career criminal in that it deems it unnecessary to distinguish between prevalence and frequency the two are inseparable and it is believed that after the age of 5 the agecrime relationship does not vary.  The research is based on cross-sectional research that retrospectively compares individuals at one time.

Both criminal propensity and criminal career methods have their limitations.  The major problem with criminal propensity is that it is limited to correlation studies and doesnt allow for researchers to thoroughly address and identify causation.  The criminal career approach is more of a longitudinal method, which does allow researchers to study causation and identify factors that affected crime.  It is, however, dependent upon exact and precise information about when crimes took place and such data is often inaccurate.