SCENARIO: 1236 Marine recruits entered training during one week in June. Marine recruits are medically examined and must be injury and illness free before beginning training. 112 refused to participate in a study to follow them during 12 weeks of training for the development of stress fractures. All recruits who consented to participate (everyone but those who refused to participate) were successfully followed for all 12 weeks. During the 12 weeks, 55 recruits developed a stress fracture. Of these 55, 26 subjects suffered stress fractures in the first 6 weeks and each of these 26 were fully recovered within 5 weeks. The shortest recovery time among those suffering stress fractures after week 6 was 7.5 weeks. At the beginning of training it was determined that 201 of participants were classified as being in "poor physical fitness." The remaining recruits were in "better than poor physical fitness." The incidence of stress fractures in the poor physical fitness group was 9.81. Hint: you may want to "draw" a timeline of the 12 week follow-up period to better understand prevalence and incidence of stress fractures over that time period. 1. What is the size of the study group? 2. What is the stress fracture incidence? 3. What is the stress fractures incidence rate? 4. What is absolute risk of stress fracture during training? 5. What is the prevalence rate of stress fractures at the beginning of training (1st day of training)? 6. What is the prevalence rate of stress fractures at the end of training? 7. Fill in the 2X2 table on the third page for stress fracture given physical fitness group? 8. What is the incidence rate of stress fractures among the better than poor physically fit recruits? 9. What PERCENT of stress fractures in the poor fit group could be reduced by increasing fitness to better than poor