### Instruction:
Who is David Oliver Siegmund

### Input:
David Oliver Siegmund (born November 15, 1941) is an American statistician who has worked extensively on sequential analysis.

Biography
Siegmund grew up in Webster Groves, Missouri. He received his baccalaureate degree, in mathematics, from Southern Methodist University in 1963, and a doctorate in statistics from Columbia University in 1966. His Ph.D. advisor was Herbert Robbins. After being an assistant and then a full professor at Columbia, he went to Stanford University in 1976, where he is currently a professor of statistics. He has served twice as the chair of Stanford's statistics department. He has also held visiting positions at Hebrew University of Jerusalem, the University of Zurich, the University of Oxford, and the University of Cambridge.

### Response:
David Oliver Siegmund (born November 15, 1941) is an American statistician who has worked extensively on sequential analysis.

Siegmund grew up in Webster Groves, Missouri. He received his baccalaureate degree, in mathematics, from Southern Methodist University in 1963, and a doctorate in statistics from Columbia University in 1966. His Ph.D. advisor was Herbert Robbins. After being an assistant and then a full professor at Columbia, he went to Stanford University in 1976, where he is currently a professor of statistics. 

He has served twice as the chair of Stanford's statistics department. He has also held visiting positions at Hebrew University of Jerusalem, the University of Zurich, the University of Oxford, and the University of Cambridge.