A recent study by the U.S. Department of Health and Human Services (2006) projects a sufficient supply of physicians to meet demand for the coming decade. As you know from your readings in this chapter, this result contradicts earlier research on the subject. The study also points out the difficulty researchers face when forecasting the demand and supply of physician services. If you were developing a model to forecast the demand for physician services over the coming decade, what demographic and economic factors would you include in your analysis and why?