Expected monetary value tree calculator

Calculate root expected payoff and preferred child at a root decision with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use root expected payoff and preferred child at a root decision to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Nodes: name, decision/chance/terminal, terminal payoff or 0
Root,decision,0 Risky,chance,0 Safe,terminal,30 Win,terminal,100 Lose,terminal,-20
Branches: parent, child, probability or none for decisions
Root,Risky,none Root,Safe,none Risky,Win,0.5 Risky,Lose,0.5
Root node
Root
Root expected payoff
40
Preferred child at a root decision
Risky
Values by node
Root: 40; Risky: 40; Safe: 30; Win: 100; Lose: -20
Decision policy by decision node
Root: Risky

Try another scenario

Nodes: name, decision/chance/terminal, terminal payoff or 0
Root,decision,0 Risky,chance,0 Safe,terminal,30 Win,terminal,100 Lose,terminal,-20
Branches: parent, child, probability or none for decisions
Root,Risky,none Root,Safe,none Risky,Win,0.25 Risky,Lose,0.75
Root node
Root
Root expected payoff
30
Preferred child at a root decision
Safe
Values by node
Root: 30; Risky: 10; Safe: 30; Win: 100; Lose: -20
Decision policy by decision node
Root: Safe
Calculation method

Calculation method

Root expected payoff

Evaluate terminal payoffs, chance-weighted child values and maximum child values at decisions, recursively.

Preferred child at a root decision

List tied best children at the root if it is a decision.

Values by node

Show each supplied node value in input order.

Decision policy by decision node

Show the maximum-payoff child choice at every reachable decision.

Symbols and units
a
Nodes: name, decision/chance/terminal, terminal payoff or 0
b
Branches: parent, child, probability or none for decisions
c
Root node

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • A finite acyclic decision/chance graph with explicit probabilities and terminal net payoffs. Decisions maximise stated expected payoff; no risk preference or real-world probability is inferred. All nodes must be reachable.
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Further reading

MIT: engineering decision analysis ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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