Author Affiliation: Institute for Healthcare Improvement, Cambridge, Massachusetts.
In Garrison Keillor's mythical hometown, Lake Wobegon, all the women are strong, all the men are good-looking, and all the children are above average. That is, of course, impossible, at least when it comes to the children. In any given population for any defined characteristic “everyone above average” is, statistically, nonsense.
Of course, the same is true of health care. Performance on anything called “good” about the care (such as reliability, waiting times, dignity, or survival) in any defined population (such as physicians, hospitals, visits, or health plans) will follow some distribution. The shape of that distribution can be orderly (such as quasi-normal, binomial, or Poisson) or disorderly, but for sure, every member cannot be above average.
Berwick DM. Measuring Physicians' Quality and PerformanceAdrift on Lake Wobegon. JAMA. 2009;302(22):2485-2486. doi:10.1001/jama.2009.1801