The general perception amongst most project and risk managers that we can somehow control the future is, says David Hancock, one of the most ill-conceived in risk management. The biggest problem is how to measure risks in terms of their potential likelihood, their possible consequences, their correlation and the public's perception of them. The situation is further complicated by identifying different categories of problem types; Tame problems (straight-forward simple linear causal relationships and can be solved by analytical methods), and 'messes' which have high levels of system complexity...