MassachusettsHospitals, GeneralBostonCaregiversRetrospective StudiesTreatment OutcomeHospitals, DistrictHospitals, TeachingHospitals, SpecialPsychiatric Department, HospitalHospitals, UniversityHospital DepartmentsHospital CostsEmergency Service, HospitalEnglandUnited StatesNursing Staff, HospitalLength of StayHospitalizationProspective StudiesHospital Bed CapacityHospitals, UrbanMedical AuditPatient AdmissionRisk FactorsEconomics, HospitalHospitals, PsychiatricHospital UnitsTime FactorsHospitals, Pediatric