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.
There are approximately 20,400 actively practicing orthopedic surgeons and residents in the United States. According to the latest Occupational Outlook Handbook (2011â2012) published by the United States Department of Labor, between 3â4% of all practicing physicians are orthopedic surgeons.