Utilization data for the study were extracted from the HMO automated systems that record all clinical costs, including hospitalizations, outpatient registrations, and pharmacy, laboratory, and radiological procedures for the child and the accompanying parent. Cost information from the general ledger was allocated using the Cost Management Information System (The Permanente Medical Group, San Francisco, Calif), purchased cost-accounting software that integrates cost and utilization. Within the system, the costs by department, medical center, patient, and service were allocated. For example, a routine 10-minute pediatric visit costs $65. The actual expenses for each service department were assigned relative values, which were used as weights for distributing the costs expensed in the department to the total volume of services provided therein. The resulting average unit cost was multiplied by the patient's actual units of service during a given visit to tabulate the direct costs of the encounter. Overhead costs were allocated to each unit of service via a step-down method. All program costs equivalent to the costs of "insurance-related" services, such as marketing, membership accounting, and related administrative costs, were excluded. As utilization accumulated for the study period under consideration, the costs of visits were aggregated. The total cost for each patient included the costs of emergency department care, primary care, specialty care, nursing, operating and recovery room care, and surgery, as well as associated radiology, pharmacy, and laboratory costs.