For the decision tree in Figure 12.13, assume Chance Events E and F are independent.
a. Draw the appropriate decision tree and calculate the EVPI for Chance Event E only.
b. Draw the appropriate decision tree and calculate the EVPI for Chance Event F only.
c. Draw the appropriate decision tree and calculate the EVPI for both Chance Events E and F: that is, perfect information for both E and F is available before a decision is made
The Correct Answer and Explanation is :
To determine the Expected Value of Perfect Information (EVPI) for Chance Events E and F in the decision tree, we follow these steps:
a. EVPI for Chance Event E Only
- Expected Monetary Value (EMV) without Perfect Information:
- Decision A:
- Outcomes:
- 0.1 probability of 20
- 0.2 probability of 10
- 0.6 probability of 0
- 0.1 probability of -10
- EMV(A) = (0.1 × 20) + (0.2 × 10) + (0.6 × 0) + (0.1 × -10) = 2 + 2 + 0 – 1 = 3
- Decision B:
- Outcomes:
- 0.7 probability of 5
- 0.3 probability of 1
- EMV(B) = (0.7 × 5) + (0.3 × 1) = 3.5 + 0.3 = 3.8
- Optimal decision without perfect information: Decision B with EMV = 3.8
- Expected Value with Perfect Information about E (EVwPI):
- With perfect information on E, choose the decision with the highest payoff for each outcome of E.
- If E = 20:
- Choose A (since 20 > 5)
- If E = 10:
- Choose A (since 10 > 5)
- If E = 0:
- Choose B (since 5 > 0)
- If E = -10:
- Choose B (since 5 > -10)
- EVwPI = (0.1 × 20) + (0.2 × 10) + (0.6 × 5) + (0.1 × 5) = 2 + 2 + 3 + 0.5 = 7.5
- EVPI for E:
- EVPI(E) = EVwPI – EMV(B) = 7.5 – 3.8 = 3.7
b. EVPI for Chance Event F Only
- Expected Monetary Value (EMV) without Perfect Information:
- As calculated above, EMV(A) = 3 and EMV(B) = 3.8
- Optimal decision without perfect information: Decision B with EMV = 3.8
- Expected Value with Perfect Information about F (EVwPI):
- With perfect information on F, choose the decision with the highest payoff for each outcome of F.
- If F = 5:
- Choose B (since 5 > 20, 10, 0, -10)
- If F = 1:
- Choose B (since 1 > 20, 10, 0, -10)
- EVwPI = (0.7 × 5) + (0.3 × 1) = 3.5 + 0.3 = 3.8
- EVPI for F:
- EVPI(F) = EVwPI – EMV(B) = 3.8 – 3.8 = 0
c. EVPI for Both Chance Events E and F
- Expected Value with Perfect Information about Both E and F (EVwPI):
- With perfect information on both E and F, choose the decision with the highest payoff for each combination of E and F outcomes.
- Combinations:
- E = 20, F = 5: Choose A (20 > 5)
- E = 20, F = 1: Choose A (20 > 1)
- E = 10, F = 5: Choose A (10 > 5)
- E = 10, F = 1: Choose A (10 > 1)
- E = 0, F = 5: Choose B (5 > 0)
- E = 0, F = 1: Choose B (5 > 0)
- E = -10, F = 5: Choose B (5 > -10)
- E = -10, F = 1: Choose B (5 > -10)
- Probabilities:
- P(E = 20) = 0.1
- P(E = 10) = 0.2
- P(E = 0) = 0.6
- P(E = -10) = 0.1
- P(F = 5) = 0.7
- P(F = 1) = 0.3
- Joint Probabilities (since E and F are independent):
- P(E = 20 and F = 5) = 0.1 × 0.7 = 0.07
- P