The AHSM is a macro model of the U.S. health sector that is benchmarked annually to the latest figures from the National Health Expenditure Accounts. It is designed to be intuitive and transparent with forecasts that can be clearly explained and understood. Within the AHSM structure, populations by age and insurance category have health care needs based upon the prevalence of medical conditions and prevailing treatment patterns. The amount of care actually acquired depends upon access to care and the amount paid. This design lends itself to analyzing historical health expenditure increases and forecasting future expenditures under alternative assumptions about the prevalence of medical conditions, treatment patterns, coverage of the uninsured, and payment rates.