Homeless people with good friends are less likely to end up in prison, according to research by Dr Lucia Corno, published in the June 2017 issue of the Economic Journal. But having friends who have done time in prison significantly raises a homeless person''s likelihood of incarceration even if they have no previous criminal record.
The study involved interviews with more than 800 homeless people in Milan, Italy, and the collection of detailed information on the names and surnames of their best friends as well as their past criminal behaviour. Analysis of these data reveals that:
• The probability of incarceration during a spell of homelessness decreases by 12 percentage points on average with one additional friend.
• But an increase by one standard deviation in the share of friends who have served previous prison sentences increases the likelihood of incarceration for a homeless person with no prior criminal experience by 23 percentage points.
To calculate the role played by friends on the criminal behaviour of homeless people, the research uses two measures:
• First, rainfall shocks as a proxy for the total number of friends: rainfall fosters a concentration of homeless people in sheltered places (for example, bridges, the underground and train stations), which raises the probability of social interactions and new friendships.
• Second, the number of inmates released by Milan''s authorities as a proxy for the number of potential criminal friends: exogenous policies driving inmates'' outflow increase the supply of potential criminal friends.
The analysis uses an innovative and representative survey among homeless people managed by the author in January 2008 in Milan. The survey involved a task force of about 350 volunteers who counted and interviewed more than 800 homeless people in one single night.
Homeless people are both territorially mobile and likely to go in and out of the state of homelessness. This means that the risk of counting and interviewing the same person twice is therefore very high. Counting and interviewing them in one night drastically reduces mistakes due to double counting.
Why do ''good'' and ''bad'' friends matter so much for criminal behaviour?
Good friends represent a source of insurance against income shocks. Intuitively, homeless people with more friends have a greater chance of surviving on the street without committing crimes, because their idiosyncratic and temporary shocks are shared among a higher number of individuals. For example, if a homeless person with many friends does not manage to find food for his daily meals, he can ask for help from his friends instead of stealing from the supermarket.
On the other hand, bad friends, which in this analysis are those with previous criminal convictions, can influence one''s criminal behaviour in many ways: by transferring criminal skills, by sharing information and by affecting the social stigma associated with illegal acts (''if all my friends are criminals, I don''t feel bad doing illegal things'').
''Homelessness and Crime: Do Your Friends Matter?'' by Lucia Corno is published in the June 2017 issue of the Economic Journal. Lucia Corno is at Queen Mary, University of London.