Why is the reduction in medical practice variation critical for cost containment?

2.3 Healthcare Finance Questions

1) Suggest some economic incentives to increase the supply of primary care (family practice) physicians, and to increase the supply of physicians in inner-city and rural areas.
2) Physician Assistants and Nurse Practitioners (PAs and NPs) are partial substitutes for physicians. What are they and what does this mean?
3) Why is the reduction in medical practice variation critical for cost containment?