As any doctor knows, economic factors increasingly impinge on health care decisions. In an effort to enlighten physicians about the "dismal science" of economics, the Annals of Internal Medicine recently published a kind of Health Economics 101.

The article, by a Canadian and British team, is based on these "10 Basic Notions of Health Economics" with translations added in parentheses.

1. Human wants are unlimited but resources are finite. (Choices are inescapable.)

2. Economics is as much about benefits as it is about costs. (The real cost of doing something may be the loss of those resources for doing something else.)

3. The costs of health care programs and treatments are not restricted to the hospital, or even to the health sector. (Keeping patients out of the hospital reduces hospital costs, but it may require more care in the community or the home.)

4. Choices in health care inescapably involve value judgments. (Treatment decisions can be subjective, and informed consent is an effort to bring the patient into that decision.)

5. Many of the simple rules of market operation do not apply in the case of health care. (Buying a heart bypass operation is not -- for lots of reasons -- like buying a valve job for your car.)

6. Consideration of costs is not necessarily unethical. (Doctors face the dilemma of doing everything possible for an individual patient while trying also to act in the wider social interest.)

7. Most choices in health care relate to changes in the level or extent of a given activity; the relevant evaluation concerns these marginal changes, not the total activity. (The question usually is not whether to develop community programs for the mentally ill but how much to spend on them and what kinds of patients to emphasize.)

8. The provision of health care is but one way of improving the health of the population. (Nutrition, sanitation and economic wealth seem to do more to prolong life than medical technology does.)

9. As a community, we prefer to postpone costs and to bring forward benefits. (It's often difficult to get support for heart disease prevention programs that may not yield obvious benefits for years.)

10. Equity in health care may be desirable, but reducing inequalities usually comes at a price. (There's no such thing as a free lunch.)