MODULE A DISCUSSION QUESTIONS 4. EMV is defined as the expected monetary value. The EMV is the expected or average return that we would realize if we were to repeat the decision an infinite number of times. “Expected value under certainty” is the expected or average return that we would realize if we were to repeat the decision an infinite number of times, each time having “perfect” or complete information and making the “best” possible decision based on that information. EVPI is defined as the expected value of perfect information. EVPI is equal to the difference between EMV (the expected or average return given that we were to make the decision based on current or available information) and “expected value under certainty” and is the maximum amount we would be willing to pay for additional (perhaps, perfect) information. Determination of EVPI is useful any time the manager has the option of expending additional resources to acquire additional information and making the decision using currently available information. 9. Maximax is the optimistic criterion. It maximizes the maximum outcome. 10. Maximin is the pessimistic criterion. It maximizes the minimum outcome. END-OF-MODULE PROBLEMS A.1 States of Nature Alternatives Very Favorable Market Average Market Large plant $275,000 Small plant Overtime Unfavorable Market Row Minimum Row Maximum $100,000 –$150,000 –150,000 275,000 75,000 $200,000 $60,000 –$10,000 –10,000 200,000 83,333 $100,000 $40,000 –$1,000 –1,000 100,000 46,333 $0 $0 $0 0 0 0 Do nothing maximin A.2 (a) (b) (c) Large plant Do nothing Small plant (a) Market Size of First Station Good Market Fair Market Poor Market Small Medium Large 50,000 80,000 100,000 20,000 30,000 30,000 –10,000 –20,000 –40,000 –10,000 Very large 300,000 25,000 –160,000 (b) maximax Row Row Minimum Maximum Row Average equally likely Row Average –160,000 50,000 80,000 100,000 300,000 20,000 30,000 30,000 55,000 maximin maximax equally likely –20,000 –40,000 Maximax decision: very large station Quantitative Module A: Decision-Making Tools 1 (c) (d) Maximin decision: small station Equally likely decision: very large station A.3 EMV (large stock) 0.322 + 0.512 + 0.22 12.2 EMV (average stock) 0.314 0.510 0.26 10.4 EMV (small stock) 0.39 0.58 0.24 7.5 Maximum EMV is large stock $12,200 A.4 EVPI $13,800 12,200 $1,600 where: $13,800 0.322 + 0.512 + 0.26 A.5 EMV (assembly line) 0.4$10,000 0.6$40,000 $28,000 EMV (new plant) 0.4 $100,000 0.6$600,000 $320,000 EMV (nothing) 0 Select the new plant option. A.6 EVPI $364,000 $320,000 $44,000 A.7 (a) (b) A.8 EMV (Alt. 1) 0.480 0.3120 0.3140 32 36 42 110 max. EMV EMV (Alt. 2) 0.490 0.390 0.390 36 27 27 90 EMV (Alt. 3) 0.450 0.370 0.3150 20 21 45 86 EVPI 117 110 7 Expected cost of hiring full-timer 0.2300 + 0.5500 + 0.3 700 $60 + 250 + 210 $520 Expected cost of part-timer 0.2 0 + 0.5350 + 0.31,000 $0 + 175 + 300 $475 Thus, use part-time lawyers. A.9 Large has EMV = $75,000 ; Small has EMV = $83,333 ; Overtime EMV = $46,333 ; and Do nothing EMV $0 . Small plant is best decision. A.10 EMV (major expansion) 150,000* EMV (minor expansion) 50,000 EMV (do nothing) 0 * Therefore, the company should do the major expansion. A.11 (a) Stock 11 cases Demand 11 Cases P 0.45 385 Demand 12 Cases P 0.35 385 Demand 13 Cases P 0.20 385 EMV $385.00 Stock 12 cases 385 420 420 $379.05 420 455 $341.25 56 329 Stock * 2 13 cases 385 112 56 273 364 The recommended course of action, based on the expected monetary value criterion, is to stock 11 cases. Instructor’s Solutions Manual t/a Operations Management (b) It should be intuitively obvious that if no loss due to overstocking is involved, one should always carry the maximum stock. This observation is confirmed by the following table. Demand 11 Cases P 0.45 385 385 385 Stock 11 cases Stock 12 cases Stock 13 cases * Demand 12 Cases P 0.35 385 420 420 Demand 13 Cases P 0.20 385 420 455 EMV $385.00 $404.25 $411.25 The recommended course of action, based on the expected monetary value criterion, is to stock the maximum of 13 cases. A.12 Profit from each case sold: $95 $45 $50 . Loss from each case produced but not sold: $45. Production (Cases) 6 6 P 0.1 300 7 300 Demand (Cases) 7 8 P 0.3 P 0.5 300 300 9 P 0.1 300 EMV $300.00 350 350 350 $340.50 350 400 400 $352.50 400 450 $317.00 45 255 8 9 * 300 90 45 210 305 300 135 350 90 45 165 260 355 She should manufacture eight cases per month Quantitative Module A: Decision-Making Tools 3 A.13 Note: All dollar values in 1,000s Build $155 Pilot works (0.5) $155 Work (0.9) $171 200 – 10 190 Fail (0.1) –$16 –150 – 10 –160 –10 Work (0.2) $38 200 – 10 190 –150 – 10 –160 Do not build $72.5 Try pilot Build –$90 Pilot fails (0.5) –$10 Fail (0.8) –$128 Do not build Decide now –$10 $0 $0 Do not build –10 Work (0.4) $80 $200 Fail (0.6) –$90 –$150 $0 The recommended strategy (EMV = 72.5) is Try pilot If pilot is success: build plant If pilot is failure: do not build plant Note: All costs/revenues have been entered at the end of the branches of the tree. Although this procedure is not required in this example due to an implicit assumption of linear utility, it is required when using a more general representation of utility. 4 Instructor’s Solutions Manual t/a Operations Management A.14 Note: All dollar values are in 1,000s. Favorable (0.4) $160 (a) Build large –20 400 –$20 Unfavorable (0.6) –$180 –300 Favorable (0.4) $32 Build small 26 80 $26 Unfavorable (0.6) –$6 –10 Favorable (0.4) $0 Do not build 0 0 $0 Unfavorable (0.6) –$0 (b) (c) Based on the expected monetary value criterion, Penny should elect to build a small plant. We can find the EVPI from the following: Expected value under certainty = (0.4) (400,000) + 0.6 (0) = $160,000 Maximum EMV = $26,000 EVPI = $160,000 $26,000 = $134,000 1% Defective (0.7) –50 3% Defective (0.2) –150 5% Defective (0.1) –250 –113 1% Defective (0.3) –50 +37 saving Buy from B –150 3% Defective (0.4) –150 5% Defective (0.3) –250 A.15 (a) Buy from A –90 –90 (b) 0 Switches should be purchased from supplier A. Quantitative Module A: Decision-Making Tools 5 A.16 (a) (b) Maximum EMV = $11,700 EVPI =13,200 11,700 =1,500 A.17 Note: All dollar values are in 1,000s. Grow (a) 150 Build large Stable –85 Grow 60 Build small Stable –45 Grow 0 Do not build Stable (b) 0 Build large wing Build small wing Do not build Population Trend Growth Stable 150 –85 60 –45 0 0 Build large wing Build small wing Do not build Population Trend Growth P 0.5 Stable P 0.5 150 –85 60 –45 0 0 (c) a f a f EMV $32.50 $7.50 $0.00 Based on the expected monetary value criterion with the assumption that the states of nature are equally likely, she should build the large wing. (d) Population Trend Growth P 0.6 Stable P 0.4 150 –85 60 –45 0 0 a Build large wing Build small wing Do not build f a f EMV $56.00 $18.00 $0.00 Based on the expected monetary value criterion, she should build the large wing. 6 Instructor’s Solutions Manual t/a Operations Management Favorable A.18 Small shop Unfavorable Favorable Survey says favorable Large shop Unfavorable No shop Use survey Favorable Small shop Unfavorable Favorable Survey says unfavorable Large shop Unfavorable No shop Favorable Small shop Unfavorable Favorable Decide now Large shop Unfavorable No shop Quantitative Module A: Decision-Making Tools 7 A.19 Small shop Survey says favorable market (0.6) +$45 Large shop Favorable (0.9) $21 Unfavorable (0.1) Favorable (0.9) $45 Unfavorable (0.1) No shop Use survey $25 $25 Survey says unfavorable market (0.4) –$5 Small shop Large shop Decide now $10 Large shop No shop –10 – 5 = –15 60 – 5 = 55 –40 – 5 = –45 0 – 5 = –5 Favorable (0.12) –$10.2 Unfavorable (0.88) Favorable (0.12) –$33 Unfavorable (0.88) No shop Small shop 30 – 5 = 25 30 – 5 = 25 –10 – 5 = –15 60 – 5 = 55 –40 – 5 = –45 0 – 5 = –5 Favorable (0.5) $10 Unfavorable (0.5) Favorable (0.5) $10 Unfavorable (0.5) 30 –10 60 –40 0 The optimal strategy is to use the survey. If the survey indicates a favorable market, then build a large shop. If the survey does not indicate a favorable market, then do nothing. 8 Instructor’s Solutions Manual t/a Operations Management A.20 (0.9) 8,500 (0.1) Info favorable (0.5) 8500 12000 –23000 (0.9) 500 (0.1) 2000 –13000 –3000 Gather more information 2750 (0.4) –9,000 (0.6) Info unfavorable (0.5) –3000 12000 –23000 (0.4) –7,000 (0.6) 2000 –13000 –3000 (0.7) 4,500 (0.3) Do not gather more information 4500 15000 –20000 (0.7) 500 (0.3) 5000 –10000 0 Your advice should be to not gather additional information and to build a large video section. A.21 (a) 5,000 Minor 10,000 Market favorable (0.5) Market unfavorable (0.5) Do nothing (b) (0.5) Market unfavorable (0.5) Major 10,000 Market favorable 100,000 –90,000 40,000 –20,000 0 EMV (major renovation) 5,000 EMV (minor renovation) 10,000* * best decision is minor renovation Quantitative Module A: Decision-Making Tools 9 Good (1/3) A.22 Small Fair (1/3) 20,000 Poor (1/3) Good (1/3) Medium Fair (1/3) 30,000 Poor (1/3) 50,000 20,000 –10,000 80,000 30,000 –20,000 55,000 Good (1/3) Large Fair (1/3) 30,000 Poor (1/3) Good (1/3) Very large Fair (1/3) 55,000 Poor (1/3) 10 100,000 30,000 –40,000 300,000 25,000 –160,000 Instructor’s Solutions Manual t/a Operations Management