Anesthesiology care demonstrates wide variation in practice. Sometimes, this variation is appropriate because the anesthesiologist is responding to patient comorbidities or procedure specific events. However, even after controlling for patient specific factors, there is a substantial amount of unexplained variation in fundamental elements of anesthesiology care. The same procedure and patient can be performed using completely different anesthetic techniques, hemodynamic management strategies, and medications. This variation in care can lead to a variation in outcome.