Metrics applicable to the ED can be grouped into three main categories, volume, cycle time, and patient satisfaction. Volume metrics including arrivals per hour, percentage of ED beds occupied, and age of patients are understood at a basic level at all hospitals as an indication for staffing requirements. Cycle time metrics are the mainstays of the evaluation and tracking of process efficiency and are less widespread since an active effort is needed to collect and analyze this data. Patient satisfaction metrics, already commonly collected by nursing groups, physician groups, and hospitals, are useful in demonstrating the impact of changes in patient perception of care over time. Since patient satisfaction metrics are derivative and subjective, they are less useful in primary process improvement. Health information exchanges can reduce nonurgent ED visits by supplying current data about admissions, discharges, and transfers to health plans and accountable care organizations, allowing them to shift ED use to primary care settings.