Analysis of Norwegian prisons shows co-offenders, brothers less likely to commit crimes
A criminal going to prison substantially cuts the chances his peers and younger brothers will be jailed in the following four years, anew paper finds.
More specifically, a person's prison stay cuts his criminal peers' chances of being charged with a crime by 51 percentage points, and his younger brothers' chances by 32 percentage points. That effect persists over the four years following sentencing, with the size of the reduction actually growing over time.
This "network analysis" allows us to think about the impact of incarceration in terms broader than just how prison impacts the individual. Does putting someone away make other criminals who are connected to them more or less likely to offend? What about the people to whom they are related? The answer to both, the new paper finds, is an emphatic "less."
This finding is based on an analysis of government data on offenders in Norway, combining information about criminals and their peer groups. The paper takes advantage of the fact that Norwegian law requires a "principle of randomization" in assigning cases to judges — offenders are randomly paired with judges, allowing the study's authors to remove many of the possible confounding variables to create a pseudo-experiment.