Shrinking the supply chain uncertainty circleAny business operating within a product delivery supply chain is faced with an Uncertainty Circle. This is a major problem area and has four segments associated with it: the supply side, the manufacturing process, the control systems and the demand side. Whereas uncertainty caused by the first two processes may be considerably reduced via the application of lean thinking principles, the last two require an understanding of total systems behaviour. In particular the availability of un-distorted market place data throughout the chain plus proven Decision Support Systems will shrink the Uncertainty Circle dramatically. The methodology is illustrated with simulation results and improved business performance observed in a real-world supply chain.