He died on Sunday at his home in Gladwyne, near Philadelphia, his daughter, Hannah Klein, said on Tuesday.
Born in Omaha, Nebraska, on September 14, 1920, Klein studied at the University of California, Berkeley and the Massachusetts Institute of Technology before joining the Penn faculty in 1958. It was there that he developed the statistical models known as the "Wharton Models" which led to his Nobel Prize.
In a biographical essay Klein said that the experience of growing up during the Great Depression had a "profound impact" on his intellectual and professional career. According to Penn's Wharton School, Klein used early version of his economic models to counter the conventional wisdom that the end of World War II would sink the U.S. economy into a depression for a few years.
But in 1946 Klein correctly predicted that pent-up demand for consumer goods combined with the purchasing power of returning soldiers would ward off a depression, according to Wharton, and later he predicted correctly that the end of the Korean War would bring only a mild recession.
Klein is survived by his wife Sonia, daughters Hannah, Rebecca, and Rachel, and son Jonathan Klein.