recently stumbled upon this article from William P. Bengen “DETERMINING WITHDRAWAL RATES USING HISTORICAL DATA”. The basic idea behind this research is that year over year fluctuations in annual returns could drastically change the standard of living of retired individuals, who rely on their investments for income. That’s why “safe” withdrawal rates need to be determined and a proper asset allocation needs to be applied. William Bengen does look into a very basic allocation of stocks and bonds, and then adjusts those target allocations annually.