How the risk of death among U.S. troops in Iraq varies by rank, service and other factors, according to a new University of Pennsylvania...

WASHINGTON — How the risk of death among U.S. troops in Iraq varies by rank, service and other factors, according to a new University of Pennsylvania analysis:

• The death rate for deployed Marines in Iraq is 8.59 per thousand per year, more than twice that of the Army, nine times that of the Navy and 20 times that of the Air Force. Navy and Air Force personnel serving in Iraq have lower death rates than comparable civilians at home.

• Enlisted personnel in the Army and Marines are significantly more likely to be killed than officers. Army privates first class and Marine lance corporals have the highest risks in their services; lieutenants have the highest risks among Marine and Army officers.

• Active-duty Army death rates are three times those of Army Reserves; the National Guard is in the middle. Marine active-duty and reserve risks are equally high.

• Older troops, women and African Americans are killed at lower rates; Hispanics, Native Americans and Asian and Pacific Islanders at higher rates.

• The Iraq troop-death rate overall is less than half the death rate for the U.S. civilian population when all ages are included.

The study, co-authored by demographers Samuel Preston and Emily Buzzell, is reported in the September issue of the journal Population and Development Review.