Conventional wisdom holds that on many college and university campuses, the president and the football coach shouldn't plot their calendars out too far, given the high rate of turnover in their jobs. But a recent study suggests that the most endangered species at a select number of institutions is the medical school dean.

The average tenure of deans at medical schools in the United States is just four years, according to "Route to the Top: A Snapshot of Deans at U.S. Medical Schools," a study by the life sciences practice at SpencerStuart, an executive search firm. That compares to 7.6 years for presidents of doctoral-granting universities and nearly 8.5 for all college chief executives, the latest data from the American Council on Education show. And while many big-time football coaches lose their jobs each year in a high-profile carousel, they tend to keep their jobs for at least half a dozen years, according to the limited available research.

Deans interviewed for the SpencerStuart study cite several reasons for the short shelf life for their colleagues. The enormous complexity of the institutions, intense time demands of the jobs, and the intensifying fiscal pressures being brought to bear on medical schools by increasing malpractice and research costs and declining state support were all blamed.

"Academic medical schools are said to be pretty much impossible organizations to run effectively because of their complexity," said Arthur H. Rubinstein, dean of the University of Pennsylvania School of Medicine.

Satisfying the institutions' many constitutencies -- faculty members and students within the school, alumni outside it and, of course, the deans' bosses in central university administration -- can also shorten deans' time spans. "There's a lot of culture clash that goes on and it's really hard to satisfy all those constituencies for a long period of time," Claire Pomeroy, vice chancellor for human health services and dean of the medical school at the University of California at Davis.

Despite those challenges, the deans reported broad satisfaction with their jobs, citing the satisfaction of helping to train future generations of doctors and shape the delivery of health care. (High pay is almost certainly another factor: The most recent survey by the College and University Professional Association for Human Resources shows that median pay for med school deans was $362,508, tops among campus leaders.)

Among other findings of the SpencerStuart study:

• Fewer than 30 percent of medical school deans had an advanced degree besides the M.D. For those with an additional degree, the Ph.D. was most common, followed by a master's in public health.
• Most deans came out of senior leadership roles in academic medicine, with internal medicine being by far the most common field for board certification, followed by pediatrics.