Solution to Witkowski TV Productions1 Witkowski TV Productions is considering a pilot for a comedy series for a major television network. The network may reject the pilot and the series, or it may purchase the program for one or two years. Witkowski may decide to produce the pilot or transfer the rights for the series to a competitor for $100,000. Witkowski’s profits are summarized in the following profit ($1000s) payoff table: Produce Pilot Sell to Competitor d1 d2 States of Nature s1 = Reject s2 = 1 Year s3 = 2 Years -100 50 150 100 100 100 (a) If the probability estimates for the states of nature are P(Reject) = 0.20, P(1 Year) = 0.30, and P(2 Years) = 0.50, what should Witkowski do? On the basis of expected value, the best thing to do is to sell to the competitor: Reject 20.0% -100 Produce Pilot FALSE 0 Expected Value 70 1 Year 30.0% 50 2 Years 50.0% 150 Witkowski Expected Value 100 Reject 20.0% 100 Sell to Competitor TRUE 0 Expected Value 100 1 Year 30.0% 2 Years 50.0% 100 100 1 David Juran. Decision Analysis with Perfect Information A more advanced concept in decision analysis involves considering how the optimal choice is affected by knowing in advance what the future state of nature will be. In this TV Production problem there is clearly a “best” choice of decision alternative for each of the possible states of nature. Here, the optimal decision for each state of nature is identified with a non-shaded cell: State of Nature Reject 1 Year 2 Years Probabilities 0.2 0.3 0.5 Net Payout if Pilot is Produced -100 50 150 Net Payout if Sold to Competitor 100 100 100 Optimal Decision Sell to Competitor Sell to Competitor Produce Pilot We calculate the expected value with perfect information by summing up the probability-weighted best payoffs for each state of nature. For this example: EVwPI 0.20 * 100 0.30 * 100 0.50 * 150 20 30 75 125 This result can be interpreted as follows: If we know ahead of time that the true state of nature will be revealed before we make the decision, then the expected value of the problem is 125 instead of 100. Therefore, perfect information (if it were available) would be worth up to 125 - 100 = 25 thousand dollars to Witkowski. This is referred to as expected value of perfect information. This number may not appear to have much practical significance, but it does provide some basis for considering whether to collect additional information before making the decision. If the expected value of perfect information is small, then there is little to be gained from additional research, no matter what the results of the new information might be. However, if the expected value of perfect information is large, then there is an opportunity to create value by conducting a research project before making the decision. B60.2350 2 Prof. Juran Decision Analysis with Sample Information For a consulting fee of $2,500, the O’Donnell agency will review the plans for the comedy series and indicate the overall chance of a favorable network reaction. PI 1 s 1 0.30 PI 2 s 1 0.70 PI 1 s 3 0.90 PI 2 s 3 0.10 PI 1 s 2 0.60 PI 2 s 2 0.40 Perfect information may be impossible to obtain, but we can often get sample information about the future states of nature, for example by performing a market research project. New information from the results of such a project might make us more confident in choosing one of the decision alternatives. The following analysis is aimed at placing a monetary value on this improvement in confidence. In this problem, Witkowski could hire O’Donnell to review the plans for the comedy series and indicate the overall chance of a favorable network reaction. Here are the conditional probabilities of each state of nature, given each possible outcome from O’Donnell (based on historical outcomes): O’Donnell Results I1 = Favorable I2 = Unfavorable PI 1 s1 0.30 PI 2 s1 0.70 Reject PI 2 s 2 0.40 1 year PI 1 s 2 0.60 PI 1 s3 0.90 2 years PI 2 s3 0.10 Using Bayes’ Law, we can use these conditional probabilities to calculate posterior probabilities (probabilities for each state of nature given each possible outcome of the O’Donnell report): Probability calculations: States Prior sj P sj P I1 s j Reject 1 Year 2-Year 0.20 0.30 0.50 0.30 0.60 0.90 Probabilities Joint Conditional P s j I1 P s j P I1 s j 0.06 0.18 0.45 Total PI 1 0.69 Posterior P s j I1 P s j I1 P I 1 0.087 0.261 0.652 The total probability of a favorable O’Donnell report is 69%. B60.2350 3 Prof. Juran States Prior sj P sj P I2 sj Reject 1 Year 2-Year 0.20 0.30 0.50 0.70 0.40 0.10 Probabilities Joint Conditional P sj I2 P sj P I2 sj Posterior P sj I2 0.14 0.12 0.05 P sj I2 PI 2 0.452 0.387 0.161 Total PI 2 0.31 The total probability of an unfavorable O’Donnell report is 31%. Now we can calculate an expected value for each decision alternative for each possible outcome of the O’Donnell project, and we can calculate an overall expected value. A revised payoff table: States of Nature No Report Get Report s1 = Reject s2 = 1 Year s3 = 2 Years d1 = Produce Pilot -100 50 150 d2 = Sell to Competitor 100 100 100 -102.5 47.5 147.5 97.5 97.5 97.5 -102.5 47.5 147.5 97.5 97.5 97.5 d1 = Produce Pilot I1 = Favorable Report d2 = Sell to Competitor I2 = Unfavorable Report d1 = Produce Pilot d2 = Sell to Competitor In the event of a favorable O’Donnell report, the expected value of producing the pilot is: EV d 1 I 1 v11 Ps 1 I 1 v12 Ps 2 I 1 v13 Ps 3 I 1 102.5 0.087 47.5 0.261 147.5 0.652 99.65 In the event of a favorable O’Donnell report, the expected value of selling to the competitor is: EV d 2 I 1 v 21 Ps 1 I 1 v 22 Ps 2 I 1 v 23 Ps 3 I 1 97.5 0.087 97.5 0.261 97.5 0.652 97.50 B60.2350 4 Prof. Juran In the event of an unfavorable O’Donnell report, the expected value of producing the pilot is: EV d 1 I 2 v11 Ps 1 I 2 v12 Ps 2 I 2 v13 Ps 3 I 2 102.5 0.452 47.5 0.387 147.5 0.161 4.20 In the event of an unfavorable O’Donnell report, the expected value of selling to the competitor is: EV d 2 I 2 v 21 Ps 1 I 2 v 22 Ps 2 I 2 v 23 Ps 3 I 2 97.5 0.452 97.5 0.387 97.5 0.161 97.5 Looking at the table here, we can see that for each possible outcome of the O’Donnell project there is an optimal strategy: Favorable O’Donnell Report Unfavorable O’Donnell Report Decision Alternative Expected Value Produce Pilot 99.65 Sell to Competitor 97.50 Produce Pilot -4.20 Sell to Competitor 97.50 ← Optimal ← Optimal The overall expected value with sample information (EVwSI) is: EV I 1 PI 1 EV I 2 PI 2 99.65 * 0.69 97.5 * 0.31 98.98 (Note that we are assuming here that we will always adopt the optimal strategy in light of whatever information O’Donnell provides.) B60.2350 5 Prof. Juran Developing an Optimal Decision Strategy (b) Show a decision tree to represent the revised problem. 8.7% Reject -102.5 Produce Pilot TRUE Expected Value 0.0 99.7 1 Year 26.1% 2 Years 65.2% 47.5 147.5 Favorable 0.7 Expected Value 0.0 99.7 8.7% Reject 97.5 Sell to Competitor FALSE Expected Value 0.0 97.5 1 Year 26.1% 2 Years 65.2% 97.5 97.5 Get O'Donnell Report FALSE 0.0 Expected Value 99.0 45.2% Reject -102.5 Produce Pilot FALSE Expected Value 0.0 -4.1 1 Year 38.7% 2 Years 16.1% 47.5 147.5 Unfavorable 0.3 Expected Value 0.0 97.5 45.2% Reject 97.5 Sell to Competitor TRUE Expected Value 0.0 97.5 1 Year 38.7% 2 Years 16.1% 97.5 97.5 Expected Value Witkowski 100.0 Do Not Get O'Donnell Report TRUE 0.0 Expected Value 100.0 20.0% Reject -100.0 Produce Pilot FALSE Expected Value 0.0 70.0 1 Year 30.0% 2 Years 50.0% 50.0 150.0 1.0 Expected Value 0.0 100.0 20.0% Reject 100.0 Sell to Competitor TRUE Expected Value 0.0 100.0 1 Year 30.0% 2 Years 50.0% 100.0 100.0 (c) What should Witkowski’s strategy be? What is the expected value of this strategy? The best thing to do is to forget about O’Donnell and sell the rights for $100,000. Note that this conclusion is not affected by whether or not Witkowski buys the report from O’Donnell. B60.2350 6 Prof. Juran Expected Value of Sample Information The expected value of sample information is calculated using this formula: EVSI = EVwSI - EVwoSI where EVSI = expected value of sample information EVwSI = expected value with sample information about the states of nature EVwoSI = expected value without sample information about the states of nature In our example, the expected value of sample information is: EVSI = EVwSI - EVwoSI 98.98 100 1.02 That means that if we pay O’Donnell the $2,500 fee, our overall expected value drops by $1,020. This implies that the O’Donnell report is worth $2 ,500 $1,020 $1,480 We would be willing to pay up to (but no more than) $1,480 for the O’Donnell report. (d) What is the expected value of the O’Donnell agency’s sample information? Is the information worth the $2,500 fee? This is one way to address the question, “How much should Witkowski be prepared to pay for the research study?” Clearly, it is not worth anything if we have to pay $2,500 for it; at that price it actually has a negative expected value. B60.2350 7 Prof. Juran Efficiency of Sample Information The efficiency of sample information is calculated using this formula: E EVSI EVPI (e) What is the efficiency of the O’Donnell’s sample information? E EVSI EVPI $1, 480 $25,000 0.0592 In other words, the market research project gives us information with less than 6% of the utility of having perfect information. B60.2350 8 Prof. Juran