Harold Cramér was born on September 1893 in Stockholm Sweeten. He studied chemistry and mathematics at the University of Stockholm. He originally planned a career in chemistry, but finally settled on mathematics, finishing his PhD in 1917.
Cramér's first work was in the area of number theory. His interest in probability and mathematical statistics began with consulting work in actuarially science with a life insurance company. He made important contributions in probability, mathematical statistics and stochastic processes. In probability, Cramér worked on the central limit theorem and proved that the sum of independent normally distributed random variables is also normally distributed. In statistics, he is particularly known for finding the lower bound on the variance of unbiased estimators of a parameter.
Harold Cramér died on October 5, 1985 in Stockholm.