Pranab Kumar Sen (7 November 1937 – 31 December 2023) was an Indian-American statistician who was a professor of statistics and the Cary C. Boshamer Professor of Biostatistics at the University of North Carolina at Chapel Hill.^[1][2]

Pranab Kumar Sen was born in Calcutta, Bengal Presidency, India on 7 November 1937,^[3] as the second of seven siblings. His father, a railway officer, died of leukemia when Sen was ten, and he was raised by his mother, the daughter of a physician.^[4] He began his undergraduate studies at Presidency College, Kolkata, initially intending to study medicine but shifting to statistics when it was discovered that he was too young for medical college.^[4] He received a B.S. from the University of Calcutta in 1955, an M.Sc. in 1957, and a Ph.D. in 1962;^[3][2][5] his doctoral advisor was Hari Kinkar Nandi.^[6][4] He taught for three years at the University of Calcutta and one more year at the University of California, Berkeley before joining the UNC faculty in 1965; although he has held visiting positions at other universities, he has remained at Chapel Hill for the rest of his career.^[3][2] He was the founding co-editor of two journals, Sequential Analysis and Statistics and Decisions,^[4] and was joint editor-in-chief of the Journal of Statistical Planning and Inference from 1980 to 1983.^[3]

Sen died in Chapel Hill, North Carolina on 31 December 2023, at the age of 86.^[7]

Sen was the author or co-author of multiple books on non-parametric statistics, the advisor of over 80 Ph.D. students, and the author of over 600 research publications.^[3][8] He is known for inventing the Hodges–Lehmann estimator independently of and contemporaneously with Hodges and Lehmann^[4][9] and for the Theil–Sen estimator, a form of robust regression that fits a line to two-dimensional sample points by choosing the slope of the fit line to be the median of the slopes of the lines through pairs of samples.^[10][11]

Sen was a fellow of the Institute of Mathematical Statistics^[12] and of the American Statistical Association.^[13] He became the Cary C. Boshamer Professor in 1982.^[3] He was the Lukacs Distinguished Visiting Professor at Bowling Green State University in 1996–1997.^[14] In 2002, he won the Gottfried E. Noether Senior Scholar Award of the American Statistical Association,^[15] and he was the 2010 winner of the Wilks Memorial Award of the ASA "for outstanding contributions to statistical research, especially in nonparametric statistics and biostatistics; and for exceptional service in mentoring doctoral students."^[16] The Government of India awarded him the civilian honour of Padma Shri in 2011.^[17] In 2012, the University of Calcutta awarded him an honorary Doctor of Science degree.^[18]

In 2007, a festschrift was dedicated to him on the occasion of his 70th birthday.^[4][8]