Excellent point by Brad but even more troubling is the misuse of return data. Asset allocators continue to use - for example- hedge fund indices which suffer massively from survivorship and back-fill bias. See Ang's book on Asset Management, for example. Remarkably, sometimes the data deficiencies are noted in the disclaimers but then ignored. The result is an unjustifiable exposure to hedge funds which suits consultants and sometimes trustees as it enables long term unrealistic return forecasts to be justified.