What does the data say about physicians' acceptance of new patients?

Aaron Carroll over at the blog The Incidental Economist (see here) investigates the often made assertion that "doctors are refusing Medicare and Medicaid patients."  Using data from a new study published in the Archives of Internal Medicine, Mr. Carroll shows there is much more to the story.  He says the study shows that:

First that the difference in the rates of acceptance of new patients with Medicare, private non-capitated patients, and self-pay patients are pretty similar. If you want to get detailed, however, the acceptance rate of private non-capitated patients went down more than the other two groups. Second, Medicaid acceptance rates were lower. They were comparable, however, to the acceptance rate of patients in private capitated plans. Also, not much changed from 2005-2008.