During the 1950s, I decided, as did many others, that many practical problems were beyond analytic solution and that simulation techniques were required. At RAND, I participated in the building of large logistics simulation models; at General Electric, I helped build models of manufacturing plants.
In 1989, I was awarded the Von Neumann Prize in Operations Research Theory by the Operations Research Society of America and The Institute of Management Sciences. They cited my works in the areas of portfolio theory, sparse matrix techniques and the SIMSCRIPT programming language.
Portfolio theory, as used by most financial planners, recommends that you diversify with a balance of stocks and bonds and cash that's suitable to your risk tolerance.