Healthcare only makes up 11 percent of health—overtreatment is worse.

. In 2016, researchers with the Determinants of Health project modeled the factors correlated with health outcomes.24 They estimated that medical care determines only about 11 percent of health—far less than individual behavior (38 percent), social circumstances (23 percent), or genetics and biology (21 percent).25 (Physical environment determines the remaining 7 percent.)26 These estimates are similar to those of several other studies. For example, J. Michael McGinnis, Pamela Williams-Russo, and James R. Knickman looked at the determinants of early death, estimating that behavior (40 percent), genetics (30 percent), and social circumstances (15 percent) were more important than medical care (10 percent).27 In addition to those estimates, the only two health insurance experiments—the Oregon Medicaid experiment discussed previously and the Rand Health Insurance Experiment—have not found a beneficial effect on physical health from people receiving comprehensive insurance.28 Although medical care is beneficial in many instances, it is often unnecessary and can be harmful. In 2012, the Institute of Medicine estimated that 30 percent of health care is unnecessary.29 In a 2015 piece in the New Yorker, Atul Gawande, a surgeon and a prolific health policy writer, observed that providers and patients often underestimate the costs of medicine.30 He cites three examples: proliferation of antibiotics for viral infections; the downsides from tests, such as increased radiation and false positives; and overdiagnosis, or positive diagnosis for conditions that develop extremely slowly and are unlikely ever to cause a patient problems.31