The independent variable remains 'incarceration' rewrite it to include people who are not incarcerated but placed in a rehab program or some other non-incarcerated setting. Your IV needs to be more broad, because you want to
A) Compare the outcomes of different correctional strategies.
B) Analyze the effectiveness of rehabilitation programs.
C) Study the social impacts of incarceration versus rehabilitation.
D) Evaluate the psychological effects of various forms of punishment.