Studies of patients at clinical facilities commonly are flawed because nothing is known about kinetic forces causing injuries, and analysis may be limited only to inpatients, with no knowledge about those not injured, those with injuries not requiring treatment, those seen only in the emergency department, or those who died at the scene. Such problems are exacerbated in trauma center studies whose populations reflect additional triage. Where alcohol is involved, acute intoxication may cause erroneous AIS, ISS and Glascow Coma Scale ratings based on initial assessment of the patient. Also, selective differences in testing for alcohol among different categories of patients can alter results.