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564   CHAPTER 13 DECISION ANALYSIS


                                     Figure 13.12 Risk Profile for PDC Project with Sample Information Showing Payoffs
                                     Associated with Optimal Decision Strategy




                                                     0.8


                                                   Probability  0.6

                                                     0.4


                                                     0.2



                                                           –10      0        10      20
                                                                     Profit (€ millions)




                                     Figure 13.12 provides a graphical representation of the risk profile. Comparing
                                     Figures 13.3 and 13.12, we see that the PDC risk profile is changed by the strategy
                                     to conduct the market research study. In fact, the use of the market research study
                                     has lowered the probability of the R9 million loss from 0.20 to 0.05. PDC’s manage-
                                     ment would most likely view that change as a significant reduction in the risk
                                     associated with the project.

                                     Expected Value of Sample Information
                                     In the PDC problem, the market research study is the sample information used to
                    The EVSI ¼ R1.73
                    million suggests PDC  determine the optimal decision strategy. The expected value associated with the
                    should be willing to pay  market research study is R15.93 million. In Section 13.3 we showed that the best
                    up to R1.73 million to
                    conduct the market  expected value if the market research study is not undertaken is R14.20 million.
                    research study.  Thus, we can conclude that the difference, R15.93 million   R14.20 million ¼ R1.73
                                     million, is the expected value of sample information (EVSI). In other words, con-
                                     ducting the market research study adds R1.73 million to the PDC expected value. In
                                     general, the expected value of sample information is as follows:


                                                               EVSI ¼jEV W SI   EV Wo SIj           (13:13)


                                     where
                                            EVSI ¼ expected value of sample information
                                          EV W SI ¼ expected value with sample information about the states of nature
                                          EV Wo SI ¼ expected value without sample information about the states of nature
                                     Note the role of the absolute value in Equation (13.13). For minimization problems
                                     the expected value with sample information is always less than or equal to the
                                     expected value without sample information. In this case, EVSI is the magnitude of
                                     the difference between EVwSI and EVwoSI; thus, by taking the absolute value of
                                     the difference as shown in Equation (13.13), we can handle both the maximization
                                     and minimization cases with one equation.




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