S. Susan Su, 44, a National Opinion Research Center senior research scientist whose field of study included drug abuse and AIDS prevention, died of ovarian cancer Sept. 2 at a hospital in Los Angeles.

For the last six years, Dr. Su had worked at the Washington office of the NORC, a social science research center affiliated with the University of Chicago.

As a senior research scientist and project director, she was the intellectual leader of long-term studies on the effects of home environment and parental behavior on adolescent drug use, substance use among women and HIV risk behavior among injection drug users.

Among her studies was one that tracked some 600 families with substance-abusing parents, depressed parents and parents without a diagnosable psychiatric disorder.

The ongoing study, supported by the National Institute of Drug Abuse, examines how family risk factors coupled with other everyday problems exacerbate the vulnerability to drug use.

A native of Taiwan, she graduated from Tunghai University in 1977 and received a doctorate in sociology from the University of Minnesota in 1989.

She had been a research associate and adjunct assistant professor at the University of Minnesota's family social science department before joining NORC in 1993.

In recent years, she served on grant application review committees for the National Institute on Drug Abuse, the National Institute of Mental Health and the Substance Abuse and Mental Health Services Administration.

She also served on the National Institute on Drug Abuse's AIDS behavioral subcommittee and the National Institutes of Health's committee of behavioral and social science of transmission and prevention of HIV infection.

Survivors include her parents; two sisters; and a brother.