In this case Dr. Steward calculated the potential lost cost savings associated with the HMO of Human Cigna and NYL Care Medicare. His analysis was based on the assumption that these HMO’s organization’s annual enrollments would have been a specific percentage higher than they actually experienced. Dr. Steward also performed research exploring Medicare risk contracting Medigap premiums Medicare HMO enrollment HMO participation in Medicare Managed Care and determinants of managed care penetration.