Jerzy Neyman (April 16, 1894 – August 5, 1981), born Jerzy Splawa-Neyman, was a Polish mathematician and statistician who spent the first part of his professional career at various institutions in Warsaw, Poland and then at University College London, and the second part at the University of California, Berkeley. Neyman first introduced the modern concept of a confidence interval into statistical hypothesis testing and co-devised null hypothesis testing (in collaboration with Egon Pearson).