29. Osberg et al. (A-31) conducted a study to identify factors that predict whether or not similarly impaired children treated at trauma centers are discharged to inpatient rehabilitation. Among other findings by the investigators were the following: In a sample of 115 subjects discharged from a trauma center to rehabilitation, 98.3 percent had head injuries; 68.5 percent of 200 subjects discharged to home had head injuries. Construct a 95 percent confidence interval for the difference between population proportions. State the assumptions that make your procedure valid.