第六章 决 策 分 析 ----Decision Analysis

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第六章 决 策 分 析 ----Decision Analysis. 决策 —— 就是人们在从事各种活动过程中所采取的决定或者选择 。 决策分析 —— 就是分析在各种条件下不同的决策行动的合理性以及在多种可能方案中选择最佳方案的过程。 决策问题通常分为 —— 确定性决策、风险性决策和不确定性决策。 确定性决策 —— 就是在决策环境完全确定的情况下进行的决策,因而所作的决策应是合理的。 风险决策和不确定性决策 是在决策环境不完全确定的情况下进行的决策,其中: 风险决策 对于其面临的自然状态发生的概率,决策者可以预先计算或估计出来; - PowerPoint PPT Presentation

Transcript of 第六章 决 策 分 析 ----Decision Analysis

  • ----Decision Analysis

  • 1 2528162216

  • 12528 1

  • 2 2

  • 2 3

  • (Alternative, State of Nature, Payoff)Aii=1mA=A1A2AmSij=1nS=S1S2Sn

  • SjAirij=RAiSj1234

  • 1(Pay off Matrix)R=rijmn i=12mj=12n2(payoff table)

  • (Decision Making without probability)

  • (,conservative approach)

    r*

  • A3

    S1S2S3

    A13614-8-8A2201600A3141033

  • (optimistic approach)

    r*

  • A1

    S1S2S3

    A13614-836A22016020A31410314

  • (Hurwicz decision criterion)

    r*01=1=0dii

  • =0.6

    = 18.4 d2=0.620+0.40= 12 d3=0.614+0.43= 9.6A1

    S1S2S3

    A13614-8-836A220160020A314103314

  • (minimum regret approach)

    h*hijSjAih*

  • (i=1mj=1n) 6

    =11A1

    S1S2S3A1021111A2160316A3226022

  • Laplace decision criterionn1/n

    r*ERAiAi

  • 1/3

    A1

  • (Decision Making with Probability)

  • 120 7

  • 25(S1)26(S2)27(S3)28(S4)PS1=0.1PS2=0.3PS3=0.5PS4=0.125A115015015015026A213415615615627A311814016216228A4102124146168

  • r*

  • 4

    A3

    25(S1)26(S2)27(S3)28(S4)PS1=0.1PS2=0.3PS3=0.5PS4=0.125A115015015015026A213415615615627A311814016216228A4102124146168

  • (expected value approach)

    Ak

  • ERA1=0.1150+0.3150+0.5150+0.1150=150.0ERA2=0.1134+0.3156+0.5156+0.1156=153.8ERA3=0.1118+0.3140+0.5162+0.1162=151.0ERA4=0.1102+0.3124+0.5146+0.1168=137.2

    A2

    25(S1)26(S2)27(S3)28(S4)PS1=0.1PS2=0.3PS3=0.5PS4=0.125A115015015015026A213415615615627A311814016216228A4102124146168

  • AkhijSjAi

  • ELA1=0.10+0.36+0.512+0.118=9.6ELA2=0.116+0.30+0.56+0.112=5.8ELA3=0.132+0.316+0.50+0.16=8.6ELA4=0.148+0.332+0.516+0.10=22.4

    A2

    25(S1)26(S2)27(S3)28(S4)PS1=0.1PS2=0.3PS3=0.5PS4=0.125A106121826A216061227A332160628A44832160

  • ERAiELAi

  • (decision tree)2

    S1S2S3ER(Ai)A13614-816.2A22016014A3141039.8

  • 1

  • 7 0.80.250030010011

  • 11

  • 2

  • (expected value of perfect information, EVPI)S1

    S1S2S3ER(Ai)A13614-816.2A22016014A3141039.8

  • rj*SjEPPIER* EVPI=EPPIER*

  • r1* =36 r2* =16 r3*=3 EPPI=0.336+0.516+0.23=19.4A1 ER*=max{16.2149.8}=16.2=ERA1 EVPI=EPPIER*=19.416.2=3.23.23.2

  • (Bayes Decision)(Sample Information)(Expected Value of sample information)(prior probabilities)(posterior probabilities)

  • 12

  • PSjSj PBk|SjSjBkPSj|BkBkSj

    3

  • ABABAPA|B10010%ABPA=10/100 PB|A=90/99

  • 90%30%75%S1S2 B1B2 B1 PB1|S1=90%PS1=75% PS2=25%PB1|S2=30% PS1|B1=0.9PS1=75%

  • S1S2B1B2B2PB2|S1=10%PS1=75% PS2=25%PB2|S2=70%

  • 9 101.50.80.20.50.30.71211.5 2

  • PB1 = P(S1)P(B1|S1)+P(S2)P(B1|S2) +PS3PB1|S3 = 0.30.8+0.50.5+0.20.3 = 0.55

  • PB2 = P(S1)P(B2|S1)+P(S2)P(B2|S2) +PS3PB2|S3 = 0.30.2+0.50.5+0.20.7 = 0.45

  • ERA1=P(S1|B1)r11 + P(S2|B1)r12 + P(S3|B1)r13 =0.436436 + 0.454514 + 0.1091(8) =21.2() ER(A2) =0.436420 + 0.454516 + 0.10910 =16() ER(A3) =0.436414 + 0.454510 + 0.10913 =10.98() ER*(B1) =max{21.21610.98}=21.2()=ERA1A1

  • ERA1=P(S1|B2)r11 + P(S2|B2)r12 + P(S3|B2)r13 =0.133336 + 0.555614 + 0.3111(8) =10.09 ERA2=0.133320+ 0.555616 + 0.31110 =11.56 ERA3=0.133314 + 0.555610 + 0.31113 =8.36 ER*B2=max{10.0911.568.36} =11.56=ERA2A2

  • ERI=P(B1)ER*(B1)+P(B2)ER*(B2) =0.5521.2 + 0.4511.56=16.862 EVSI=ERIER* =16.86216.2=0.6621.5

  • PDCPDC (1)30 (2)60 (3)90

  • PDC : (s1)(s2)(d1)(d2)(d3)8142075-9

  • . ()1. : max max rij=r31=20 , d3 : . 2. max min rij=r12=7 , d1: .

    PDC : (s1)(s2)max rijmin rij(d1)(d2)(d3)8142075-98142075-9

  • 3. : min max hij=h22=6 , d2 : .

    PDC : rijhijmax hij(s1)(s2)(s1)(s2)(d1)(d2)(d3)8142075-91260021612616

  • . () 1. PDC0.80.2 ER(d1)=0.8 8+0.2 7=7.8 ER(d2)=0.8 14+0.2 5=12.2 ER(d3)=0.8 20+0.2 (-9)=14.2 , d3: .

    PDC : (s1)(s2)ER(di)P(s1)=0.8P(s2)=0.2(d1)(d2)(d3)8142075-97.812.214.2

  • PDC14.214.212.27.8

  • . () 2. () , , $ 20 million . , $ 7 million . , EPPI=0.8 20+0.2 7=17.4 d3: , $ 14.2 million . , : EVPI=EPPI ER*=17.4 14.2 = 3.2

  • 1. (indicators) , (Sample Information, or Indicator) . PDC, (two indicators): I1=(favorable market research report) () I2=(unfavorable market research report) () . ()

  • 2. Bayes,. .

    (I1)(I2)(s1)(s2)P(I1/s1)=0.9P(I1/s2)=0.25P(I1/s2)=0.10P(I2/s2)=0.75

  • (I1)

    Sj

    P(sj)P(I1/sj)

    P(I1 sj)

    P(sj/I1)s1s20.80.20.90.250.720.05P(I1)=0.770.93510.0649

    (I2)

    Sj

    P(sj)P(I2/sj)

    P(I2 sj)

    P(sj/I2)s1s20.80.20.10.750.080.15P(I1)=0.230.34780.6522

  • 3. ()8.1315.8218.111.098.137.3518.1113.427.94

  • 4. : PDC$ 15.82 million . d3: , $ 14.2 million . , PDC: , : , ; , ; 5. EVSI=15.8214.2=1.60 million $ 6. E=EVSI/EVPI 100%=1.60/3.2 100%=50%

  • 7. (risk profile) . , 8. PDC

    -9 514200.77 0.06=0.050.23 0.65=0.150.23 0.35=0.080.77 0.94=0.72

  • (utility and decision making)

  • 10 ABA0.70.3B0.90.113 13

    ABAB

  • 101000

  • A1A2A1x2A2px11px3x1>x2>x3,ux1x1A1A2 pux1+1pux3=ux2x2x1x3434

  • 1x1x2x3ppA1A22px1x3x2x2A1A23px2x3x1px1x3A1A2Von NeumannMorgensternVMp=0.5x1x3 0.5ux1+0.5ux3=ux2x2

  • 11 20050VMu200=1u50=0

  • 1200.5600.251700.75500200153

  • 153

  • 12 AB0.60.420050120203

  • ERA=0.6200 + 0.450=100 ERB=0.6120 + 0.420=64A EuA= 0.61 + 0.40 = 0.6 EuB= 0.60.5 + 0.40.1 = 0.34A EuA= 0.61 + 0.40 = 0.6 EuB= 0.60.8 + 0.40.35 = 0.62B

  • , ,:

    : P(s1)=0.3P(s2)=0.5P(s2)=0.2A (d1)B (d2)(d3)3000050000 0 20000-20000 0-50000-30000 0

  • 1.: ER(d1)=0.3 30000+0.5 20000+0.2 (-50000) =9000 ER(d2)=0.3 50000+0.5 (-20000)+0.2 (-30000) =-1000 ER(d3)=0.3 0+0.5 0+0.2 0 =0, A.::30000, , d1d2, d3;

  • 2. : A1: p50000(1-p)-50000; A2: 1X;: p, A1A2?: U(X)=pU(50000)+(1p)U(-50000) , X. X=30000, :p=0.95, U(30000)=0.95U(50000)+(10.95)U(-50000) =0.95 10+0.05 0 = 9.5

  • 2. ,

    (X)5000030000200000-20000-30000-500000.950.900.750.550.4010.09.59.07.55.54.00.0

  • 3. : ER(d1)=0.3 9.5+0.5 9.0+0.2 0.0=7.35 ER(d2)=0.3 10+0.5 5.5+0.2 4.0=6.55 ER(d3)=0.3 7.5+0.5 7.5+0.2 7.5=7.5, d3, ..

    P(s1)=0.3P(s2)=0.5P(s2)=0.2A (d1)B (d2)(d3)9.5107.59.05.57.50.04.07.5

  • ;;;;, ;

  • THE END