Any patient scheduled for surgery hopes, and maybe assumes, that his surgeon will do a high-quality job. Surgeons know better. Nearly three decades of research have made clear that some hospitals and surgeons have significantly better outcomes than others.

Exactly how to measure the quality of a surgeon’s skills, however, is up for debate. Surgical volume—the number of operations of a specific kind performed at a hospital or by an individual surgeon—is known to be a good marker for quality. But it’s not perfect. For example, looking only at hospitals that perform at least 125 bariatric surgeries per year, a recent review found that the rate of serious complications ranged from less than 1 percent to more than 10 percent.

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