In this type of model, the role of the medical director includes the teaching of the practitioners, in both the classroom and the clinical setting. Most such training programs tend to feature very large components of hands-on clinical experience, generally conducted in the emergency room or similar environment, and usually in a one-to-one ratio with the physician. The medical director will be responsible for examination of the candidate and certification of their ability to practice safely. The medical director will have a major role in determining the permitted scope of practice, and will investigate practice-related complaints. In some jurisdictions the medical director will be responsible for medical quality assurance, although there are some where this function is performed by the practitioners themselves. Finally, the medical director (or other emergency physicians) may be responsible for providing the required medical 'back up' when the practitioner reaches the limit of their scope of practice.