Russian–U.S. mathematician and statistician who helped to establish the statistical theory of hypothesis testing. Neyman was a principal founder of modern theoretical statistics. In 1968 he was awarded the prestigious National Medal of Science.

After serving as a lecturer at the Institute of Technology, Kharkov, in the Ukraine, from 1917 to 1921, Neyman was appointed statistician of the Institute of Agriculture at Bydgoszcz, Pol. In 1923 he became a lecturer at the College of Agriculture, Warsaw, and joined the faculty of the University of Warsaw in 1928. He served on the staff of University College, London, from 1934 to 1938, and then emigrated to the United States, where he joined the faculty of the University of California at Berkeley, becoming chairman of a new department of statistics in 1955. There he built, with the help of a growing number of statisticians and mathematicians who studied under him, what became known as a leading world centre for mathematical statistics. A highly successful series of symposia on probability and statistics were carried out under his guidance.

Neyman's work in mathematical statistics, which includes theories of estimation and of testing hypotheses, has found wide application in genetics, medical diagnosis, astronomy, meteorology, and agricultural experimentation. He was noted especially for combining theory and its applications in his thinking.