[1] Tilley graduated from California State University, Northridge in 1972.
She became a professor at Case Western Reserve University in 1998,[1] and in 1999, moved to the Medical University of South Carolina as chair of the Department of Biostatistics, Bioinformatics and Epidemiology.
She returned to the University of Texas School of Public Health in 2009, as Lorne D. Bain Distinguished Professor and head of the Division of Biostatistics.
[4] In 1992, Tilley was elected as a Fellow of the American Statistical Association.
[1] Tilley was president of the Statistics Section of the American Public Health Association in 1991,[1] and president of the Caucus for Women in Statistics for the 1993 term.