It is plausible that distance, quality, and hospital charges all influence which hospital patients (and their referring physicians) choose. Several researchers have estimated conditional choice models that explicitly incorporate the existence of competing hospitals. To be useful for hospital administrators, health planners and insurers, however, estimates must be made for specific types of patients and include entire market areas. Data sets meeting these requirements have many combinations of hospitals and locations with zero patients. This raises computational difficulties with the linear estimation techniques used previously. In this paper, we use data on patients undergoing cardiac catheterization in several market areas to assess alternative estimation techniques. First, we estimate the conditional choice model with the two techniques used previously to transform the non-linear choice model. These involve using as a reference (1) a single hospital, or (2) the geometric mean of all the hospitals in the market. When there are many zeros, these techniques require extensive adjustments to the data which may lead to biased estimators. We then compare these results with maximum likelihood estimates. The latter results are substantively and significantly different from those using traditional techniques. More importantly, the linear estimates are much more sensitive to the proportion of zeros. We thus conclude that maximum likelihood estimates are preferable when there are many zeros.

For over a decade, the National Bureau of Economic Research has sponsored the Economics of Aging Program, under the direction of David A. Wise. The program addresses issues that affect the well-being of individuals as they age and a society that is composed increasingly of older people.

Within the next twenty years, an unprecedented proportion of Americans will be over sixty-five. New research in the economics of aging is an essential element of understanding what the future holds for this aging population. Inquiries in the Economics of Aging presents both empirical papers that consider questions that are fundamental to public policy and more theoretical contributions that lay new groundwork for future research in the economics of aging.

Inquiries in the Economics of Aging provides a timely overview of some of the most important questions facing researchers on aging and outlines new techniques and models that may help to answer these questions. This important volume will be of great interest to specialists and policy makers as it paves the way for future analysis.

Questions of equity and efficiency have always plagued our national health-care system. Not all the billions spent in this area go for actual restoration of health. Many of the expenditures are for various procedures, tests, prescriptions, etc., that may or may not be necessary. How can we determine the optimum system of health care? Fuchs thinks that the application of the principles of economics can help in arriving at the right mix of market competition, government regulation, and professional control. He also devotes special attention to the impact of the increasing number of programs in health education and promotion. A topical analysis, which should be required reading for policymakers. Recommended for academic and large public libraries. - M. Balachandran, Univ. of Illinois Lib., Urbana-Champaign