[4][7] Both her parents had advanced degrees;[6] her father, pianist Thomas Flagg, became dean of fine arts at Howard University.
[3][9] As a master's student at Maryland, she became interested in statistics after taking a class on the subject from Piotr Mikulski.
[10] She completed her Ph.D. in statistics at George Washington University in 2001, supported by the Gates Millennium Scholars Program as one of their first cohort of students.
[7][10][11] From 2001 to 2004, Sellers held a visiting assistant professorship and National Science Foundation supported postdoctoral scholarship at Carnegie Mellon University, where she worked with Bill Eddy and Stephen Fienberg.
[9] She moved to Georgetown in 2006, at a time when the university was beginning a program in statistics,[7] and took a second affiliation with the Census Bureau in 2015.