…only an extremely small portion of administrative costs are related to the dollar value of health care benefit claims. Expressing these costs as a percentage of benefit claims gives a misleading picture of the relative efficiency of government and private health plans.Medicare beneficiaries are by definition elderly, disabled, or patients with end-stage renal disease. Private insurance beneficiaries may include a small percentage of people in those categories, but they consist primarily of people are who under age 65 and not disabled. Naturally, Medicare beneficiaries need, on average, more health care services than those who are privately insured. Yet the bulk of administrative costs are incurred on a fixed program-level or a per-beneficiary basis. Expressing administrative costs as a percentage of total costs makes Medicare’s administrative costs appear lower not because Medicare is necessarily more efficient but merely because its administrative costs are spread over a larger base of actual health care costs. When administrative costs are compared on a per-person basis, the picture changes. In 2005, Medicare’s administrative costs were $509 per primary beneficiary, compared to private-sector administrative costs of $453.
Via Greg Mankiw