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.
Starting with the physicians... According to the American Board of Pediatrics, as of 2011, There are 52,673 currently certified general pediatricians in the U.S., with a national ratio of 1400 children per pediatrician. [The Journal of Pediatrics, Vol. 159 Issue 6, Pages 1036-1040.e3, December 2011]