Medium-Term Criminal Justice Impact Fade-Out

In Simple Words

Think of placing a temporary speed bump on a residential street during the summer; while drivers slow down while passing over it, once the speed bump is removed, vehicle speeds gradually return to their previous baseline over the following years unless permanent road changes are constructed.

Research question

Short-term youth employment interventions frequently achieve immediate behavioral reductions, but evaluating whether these gains persist as long-term structural changes over subsequent years remains a key challenge for social policy.

Participants

N = 163,447 youth (5,092 at-risk youth with prior arrests, 158,355 low-risk youth aged 16+), New York City.

Study Design

Longitudinal Two-Stage Least Squares (2SLS) instrumental variable tracking across 1-year, 3-year, and 5-year post-program windows (excluding summer treatment months).

Results

Post-program arrest and conviction effects up to five years show no statistically significant impacts for either group. Among at-risk youth, felony arrest reductions show a persistent directional decrease of roughly 10% (-2.60 percentage points at 1 year, -4.51 at 3 years [p < 0.10], -2.81 at 5 years), while low-risk youth yield precisely estimated zeroes (+0.175 percentage points at 5 years, p > 0.10).

Takeaway

1. Supplement short-term summer jobs programs with multi-year continuous supportive programming to sustain long-term crime reduction outcomes.

Read alongside the research

Plain-English glossary

Original explanations, informed by the references below. Examples are illustrations, not data from the studies above. The research text stays unchanged.

Longitudinal study

A study that checks the same group of people at different times. This lets researchers examine how things change over time.

ExampleResearchers ask the same workers about their wellbeing at the start, after three months and after six months.

NICE · Longitudinal study ↗Read more about longitudinal study →

Percentage points

The difference between two percentages.

ExampleA rise from 40% to 50% is 10 percentage points. Relative to the starting value, that is a 25% increase.

Office for National Statistics · Percentages ↗Read more about percentage points →

Statistically significant

A label used when a result passes a chosen statistical threshold, often p < 0.05. It does not show how large or useful an effect is. A result that is not statistically significant does not prove there is no effect.

ExampleA study reports p = 0.03 against a 0.05 threshold. It passes that test, but the effect could still be too small to matter.

American Statistical Association · Statement on p-values ↗Read more about statistically significant →

Related findings

• Post-Program Behavioral Persistence vs. Incapacitation →Crime & justice

  If a program only works by keeping someone busy, bad choices return immediately when the supervisor leaves; but if the experience teaches internal emotional steering, the person continues making safer choices even after walking away from the structured environment.

• Contemporaneous Crime Reduction in At-Risk Youth →Crime & justice

  Think of a teenager's summer schedule as a bucket of free time; if the bucket is empty, it easily fills up with risky behavior and bad decisions. Filling that bucket with a 25-hour-a-week job is like putting a lid on the bucket during the day, leaving no room or opportunity to get into trouble.

• Contemporaneous Incapacitation via Program Hours Allocation →Crime & justice

  Imagine a youth's peak hours for getting into trouble are weekday afternoons. Assigning them to a job requiring 25 structured hours per week physically occupies those peak hours, leaving insufficient time and opportunity to engage in illegal activities during the program duration.

• Crime-Type Heterogeneity in Social Interventions →Crime & justice

  Learning emotional self-control helps a driver avoid throwing a punch during road rage, but it does not remove the financial temptation to take an unattended wallet from a counter. Conflict-resolution skills alter interpersonal behavior without automatically altering economic incentives for theft.