Here is a brief outlining a number of studies done on re-offending rates between juveniles tried and sentenced in the juvenile system versus the adult system.
Read the descriptions of studies"A number of studies have compared recidivism rates of youth who are tried in criminal court with youth who are retained in the juvenile system. Two studies
approached the question from diff erent perspectives, yet came to the same basic conclusion: youth subjected to the more punitive adult court system
showed higher rates of recidivism and reoff ended more quickly than comparable youth in the juvenile system. Other studies have reached the same conclusion."
"A study of Florida crime records found very different results than the national study.14 Th is study analyzed the impact of moving from a more lenient juvenile
system to a more punitive adult system on the rate at which adolescents committed crime. Deterrence theory predicts that being subject to the more
punitive sentencing of the adult system should lead to a decline in crime as juveniles turn 18. However, an analysis of Florida arrest records showed a large increase in the rate at which juveniles were arrested and punished when they turned 18, and no corresponding decline in criminal behavior."