ABSTRACT
Among the kinds of uncertainty that we might deal with are uncertainties about future economic events: prices, sales levels, market shares, costs, lives of assets and projects, interest rates, and even availability of nancing. All these factors, and more, are important to the success of most business ventures, and most of them vary over time-we do not know what they will be in the future. Without knowing what will happen in the future, it is di cult to be sure we are making the right decision now. Yet, we want to make the best decision possible under the circumstances of our limited knowledge and considerable ignorance. In this regard, models can help us. All the modeling and planning in the world cannot assure us that we will have made the best decision when viewed with the bene t of hindsight. All we can hope to do is to arrive at the best decision possible given the information that is available before the fact.
