One such cross-sectional study included 319 adolescents, between the ages of 16 and 19 years, who were full-time students in high school or college and were working for pay, at least 5 hours per week, in a formal organization (Frone, 1998). The study population was not randomly sampled but rather recruited through advertisements. Participants were 40% male and 68% white. Other factors associated with elevated occupational injury risk in this study population were self-reported larger workload, more boredom at work, and less extensive supervisor monitoring.