Selection Bias Selection bias occurs when the selection of participants in one group results in a different outcome than the selection for the other group
1 As of 2015, there are more than 96,000 osteopathic medical physicians in the United States.  By 2020, the number of osteopathic medical physicians will be over 100,000, say expert predictions, according to the American Medical Association.
The number of general surgeons needed to adequately serve the population is estimated to be at least 7 per 100,000 people. Currently, there are about 18,000 active general surgeons in the US, or 5.8 per 100,000 people. The ratio of general surgeons per 100,000 population has dropped by 26% in the last 25 years. Medical schools are expanding class sizes and a few new schools are opening, but it will take several years for the impact of these changes to be felt.