Understanding whether criminal behavior is “contagious” is important for law enforcement and
for policies that affect how people are sorted across social settings. We test the hypothesis that
criminal behavior is contagious by using data from the Moving to Opportunity (MTO)
randomized housing-mobility experiment to examine the extent to which lower local-area crime
rates decrease arrest rates among individuals. Our analysis exploits the fact that the effect of
treatment group assignment yields different types of neighborhood changes across the five MTO
demonstration sites. We use treatment-site interactions to instrument for measures of
neighborhood crime rates, poverty and racial segregation in our analysis of individual arrest
outcomes. We are unable to detect evidence in support of the contagion hypothesis.
Neighborhood racial segregation appears to be the most important explanation for acrossneighborhood
variation in arrests for violent crimes in our sample, perhaps because drug market
activity is more common in high-minority neighborhoods.
social experiment
This paper presents results from an experimental evaluation of an earnings supplement program offered
to long-term welfare recipients in two Canadian provinces. The program -- known as the Self-Sufficiency
Project - provides a supplement equal to one-half of the difference between an earnings target ($2,500 or
$3083 per month, Canadian dollars, depending on the province) and the individual's actual earnings. The
supplement is similar to a negative income tax with two important differences: (1) eligibility is limited to
long-term welfare recipients who find a full-time job (30 hours per week or more); and (2) the supplement
payment is based on individual earnings rather than family income. The evaluation is based on a
randomized design that will follow 6,000 individuals for five years. Early findings for a first cohort of
2,000 individuals observed over 18 months of program eligibility suggest that the financial incentives of
the Self-Sufficiency Program significantly increase labor market attachment and significantly reduce
welfare participation.
The Moving to Opportunity (MTO) demonstration assigned housing vouchers via random
lottery to low-income public housing residents in five cities. We use the exogenous variation in
residential locations generated by the MTO demonstration to estimate the effects of
neighborhoods on youth crime and delinquency. We find that the offer to relocate to lowerpoverty
areas reduces the incidence of arrests among female youth for violent crimes and
property crimes, and increases self-reported problem behaviors and property crime arrests for
male youth -- relative to a control group. Female and male youth move through MTO into
similar types of neighborhoods, so the gender difference in MTO treatment effects seems to
reflect differences in responses to similar neighborhoods. Within-family analyses similarly show
that brothers and sisters respond differentially to the same new neighborhood environments with
more adverse effects for males. Males show some short-term improvements in delinquent
behaviors from moves to lower-poverty areas, but these effects are reversed and gender
differences in MTO treatment effects become pronounced by 3 to 4 years after random
assignment.