New government research has found large and growing" disparities in life expectancy for richer and poorer Americans, paralleling the growth of income inequality in the last two decades. Life expectancy for the nation as a whole has increased, the researchers said, but affluent people have experienced greater gains, and this, in turn, has caused a widening gap. One of the researchers, Gopal K. Singh, a demographer at the Department of Health and Human Services, said "the growing inequalities in life expectancy" mirrored trends in infant mortality and in death from heart disease and certain cancers [and] that federal officials had found "widening socioeconomic inequalities in life expectancy" at birth and at every age level. He and another researcher, Mohammad Siahpush, a professor at the University of Nebraska Medical Center in Omaha, developed an index to measure social and economic conditions in every county, using census data on education, income, poverty, housing and other factors. In 1980-82, Dr. Singh said, people in the most affluent group could expect to live 2.8 years longer than people in the most deprived group (75.8 versus 73 years). By 1998-2000, the difference in life expectancy had increased to 4.5 years (79.2 versus 74.7 years), and it continues to grow, he said. After 20 years, the lowest socioeconomic group lagged further behind the most affluent, Dr. Singh said, noting that "life expectancy was higher for the most affluent in 1980 than for the most deprived group in 2000. If you look at the extremes in 2000," Dr. Singh said, "men in the most deprived counties had 10 years' shorter life expectancy than women in the most affluent counties (71.5 years versus 81.3 years)." The difference between poor black men and affluent white women was more than 14 years (66.9 years vs. 81.1 years).