Dale T. Mortensen, Top Labor Economist, Dies at 74 Prof. Dale Mortensen Lars Krus/Aarhus University, via Reuters Dale T. Mortensen, an economist whose pioneering work on labor markets won a Nobel and helped governments and policy makers better understand the stubborn complexities of unemployment, died on Thursday at his home in Wilmette, Ill. The cause was cancer, his son, Karl, said. Professor Mortensen was one of three economists who shared the 2010 Nobel Memorial Prize in Economic Sciences for their work on a line of economic thinking known as search theory. Together he and the other two laureates, Peter A. Diamond of the Massachusetts Institute of Technology and Christopher A. Pissarides of the London School of Economics, developed a model to help explain why even in times of economic health, when employers have many job openings, it can be hard for unemployed people to find work, and conversely, why employers may have a hard time filling open positions even during periods when the pool of available workers is large. The answer, which had to do with the facts that neither people nor jobs are cookie-cutter units and that there are inefficiencies associated with matching them up, can be applied to housing, public finance, even dating - any market where buyers cannot automatically link up with sellers and where traditional forces of supply and demand do not play out. His work helped steer policy debates about joblessness beyond the level of worker pay and unemployment benefits and toward other factors, among them interest rates and search costs. His books included "Wage Dispersion: Why Are Similar Workers Paid Differently?" (2003) and "Job Matching, Wage Dispersion and Unemployment" (2011), written with Mr. Pissarides. In a comment posted as part of an obituary on the website of Northwestern University, where Professor Mortensen had taught since 1965, Robert E. Lucas, the John Dewey distinguished service professor in economics at the University of Chicago, said Professor Mortensen "combined sophisticated economic theory and careful empirical work in ways that will continue to inspire economic researchers for decades to come." Dale Thomas Mortensen was born on Feb. 2, 1939, in Enterprise, Ore. His father, a Danish immigrant, was a forest ranger, and Dale developed a love of the outdoors as a child that continued through his final days, his son said. He graduated from Willamette University in Salem, Ore., with a bachelor of science degree in economics, and earned his Ph.D. from Carnegie Mellon. He joined the Northwestern faculty in 1965 and stayed at the university for his entire career except for a stint as a visiting professor at a university in Denmark. It was during a luncheon on a return trip to Denmark for an academic conference that he learned he had won the Nobel. In addition to his son, Professor Mortensen is survived by his wife of 50 years, Beverly, a religion scholar on the Northwestern faculty; two daughters, Lia DuBarry Mortensen and Julie Mortensen Glanville; eight grandchildren; and two brothers, Arne and Irving. Though Dr. Mortensen made his career in what many a college student has considered a dry discipline, his outside interests were more lively. He and his wife were patrons of the symphony, opera and theater, and he was a member of his church choir, which his wife directed. "He was a big singer," Karl Mortensen said.