This study was conducted to evaluate a forecast model designed to describe a vocational high school for runaway students. The study included 2000 adolescents from the KEEP(Korean Education and Employment Panel). A Data mining decision tree model revealed that: (1) Suicide ideation was a risk factor for running away among smokers. (2) High self-evaluation was a risk factor for running away among individuals that smoked and had no suicide ideation. (3) Drinking was predicted as a risk factor for no smokers, while family life dissatisfaction was predicted as a risk factor among non-smokers that drank. (4) Negative relationship with mother was predicted as a risk factor among non-drinking non-smoking.