Simplify the following text for a Grade 11 native English-speaking person.
Original: He was also a research professor of economics and statistics at the University of Illinois , a consultant to the RAND Corporation for the University of Chicago and a consultant to the U.S. government .
Simplified: He was also a research professor of economics and mathematical statistics at the University of Illinois , a consultant to the RAND Corporation through the University of Chicago and a consultant to the U.S. Bureau of the Budget .