How We Looked Inside

For this article, BusinessWeek built up a picture of the broad health-care industry using job data from the Bureau of Labor Statistics. At the heart of the health-care sector, of course, is private health services, ranging from mega-health systems such as the Cleveland Clinic down to small private physicians' practices. But the health-care sector also includes companies that are developing and manufacturing drugs, medical supplies, and equipment; health-insurance providers; wholesalers and retailers of drugs, medical equipment, and supplies; health charities; and government-run hospitals. So a biotechnology company such as Amgen Inc. (AMGN )would be in the health-care sector, as would the American Heart Assn. and the hospital system run by the Veterans Affairs Dept.

Using this definition, the health-care sector represents 12% of the total workforce today. Hospitals alone, private and public, employ 5.7 million workers -- over 4% of the total workforce.

Our analysis used 12-month averages to smooth out statistical blips, a big issue at the state level. The end date, July, 2006, is the latest month for which job figures for all industries are available. The baseline date, July, 2001, is exactly five years earlier, thereby avoiding problems with seasonal variation.

That date also has the virtue of being very close to the month -- June, 2001 -- when 12-month average employment hit its high for the boom. That means employment in today's reasonably good labor market is being compared with employment at the previous peak, which is the right way to do the calculations.

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