expected-value
Concept of the skill
What it is: Expected value is a decision method for choosing under quantified uncertainty. It ranks actions by summing probability times value across each possible outcome, then comparing the resulting expected payoff or utility.
Mental model: Build a payoff table. Rows are actions, columns are possible outcomes, and each outcome has a probability and a value in the same unit. Expected value is the weighted total for each row after costs, checked against constraints.
Why it exists: Agents over-weight vivid upside, visible downside, or the option with the best story. Expected value forces each option to state how often each outcome happens, how much it matters, what it costs, and whether the result survives sensitivity checks.
What it is NOT: It is not Bayesian updating, broad backlog prioritization, second-order consequence discovery, formal valuation, or a guarantee that the average outcome will occur once.
Adjacent concepts: Expected utility, expected monetary value, payoff matrices, decision trees, break-even probability, sensitivity analysis, value of information, risk of ruin.
One-line analogy: Expected value is a scale that weighs every future by both its size and its chance, then compares the total weight of each option.
Common misconception: A positive expected value is not automatically a good decision. If the downside can kill the project, violates a constraint, or depends on made-up probabilities, the correct next move may be mitigation or information-gathering.