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.
Approximately 159,000 nurse practitioners are in practice in the United States today. With practices squeezing costs and a growing shortage of primary-care physicians, NPs are fast becoming the resource of choice for physicians looking to expand their practices and resolve day-to-day patient challenges.