Nói chung, tính toán phân phối rủi ro ngụ ý trung lập về các dẫn xuất sẽ được chính xác hơn, mặc dù số lượng dựa. Các khi nhu cầu là một chức năng ngẫu nhiên giá ngẫu nhiên, một cách tiếp cận tương tự có thể được sử dụng bằng cách xem xét một hạn chế ngẫu nhiên, | 408 7 RISK AND SUPPLY CHAINS Finally D1 D1 ự rf 2w1 1 Rf r - r Õ . More generally calculating the implied risk neutral distribution in terms of derivatives will be more precise albeit numerically based. When the demand is a random function of random prices as well a similar approach can be used by considering a stochastic constraint summarizing the potential demand realizations in terms of an order and a portfolio of derivatives contracts that replicate that is can meet the demand at all prices and in all situations. The implication of our approach is that a retailer acting on a risk neutral probability . in complete markets is subject to the same laws of finance presuming that without assuming risks there are no profits. In other words a retailer acting as an intermediary between say the supplier and end market customers must have some informational advantage or some other advantages that will allow him to make arbitrage profits. Of course in a practical setting the retailer and the supplier base their analyses on both observations of market behavior and their instructed beliefs in regard to the future states of potential prices. Such beliefs recur both with respect to the demand and price uncertainty which are combined in retailers risk attitudes in determining an optimal order policy. The risk neutral probability imbeds these beliefs assuming their expression in the price of derivatives while the relationship between demand and price has made it possible to remain within the simple complete markets framework that has allowed our calculations. A generalization to more complex situations can be considered as well. From the analysis in the previous section we clearly saw that our results depend on knowing the risk neutral probability. In practice however retailers and suppliers possess private information which can lead them to believe that they have in fact an informational advantage. In this case while market prices are what they are a retailer for .
