I don't think it includes over head - overhead would include rent (depending on location/state - +1,200 per month), phone, utilities and malpractice insurance (the most expensive of all) - there are pros and cons to private practice(solo versus working in a group) - some make out better than others, depending on the type of practice. It also depends of the ratio of types of patients - medicare, insurance, self pay.
I think most folks start out out with a mixed private practice/hospital based then phase out working in a hospital once they build a patient base. I think (I can't remember where I heard this) it can take upwards of 10 years to build a solid F/T private practice.