Dr. Xie's methodological research focuses primarily on the analysis of complex survey data, and she has a special interest in small-area estimation. She has served as the lead biostatistician for a Penn-based collaboration with the National Cancer Institute, the National Center for Health Statistics, the Centers for Disease Control and the University of Michigan, developing new methods for combining information from national surveys such as the Behavioral Risk Factor Surveillance System and the National Health Interview Survey. Methodologies and estimates can be found at https://sae.cancer.gov/nhis-brfss/

Her applied-research interests center on chronic kidney disease and on disability. She leads the biostatistical team for the Chronic Renal Insufficiency Cohort (CRIC), a large multi-center cohort study funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). In disability research, she works closely with Drs. Sean Hennessy and Hillary Bogner to study factors that affect changes in function among the elderly.

Dr. Xie joined Penn's faculty in July 2007 after completing three years in the CCEB as an instructor.