Oil wildcatter (influence diagram)
The canonical decision-analysis teaching problem as a compact influence diagram — a drill decision informed by a seismic test, the uncertain oil state, and the profit objective, wired as a clean acyclic graph instead of an unrolled tree.
For the decision-analysis instructor
What this shows
The textbook oil-wildcatter problem drawn the way a decision analyst frames it first — as an influence diagram rather than a fully unrolled decision tree. One rectangle for the drill decision, two ovals for the uncertainties (whether oil is present, what the seismic test reads), and one octagon for the profit objective. The whole problem is four nodes and four arcs, no matter how many states each variable could take.
The arcs carry the structure. Seismic -> Drill is a dashed informational arc: the seismic result is observed before the drill choice is made — that's the entire reason the test is worth running. Seismic -> Oil is a relevance arc (the reading is conditioned on the true oil state), and Oil -> Profit plus Drill -> Profit are functional arcs feeding the payoff. This mode is deliberately structural — it shows what informs what, without solving for expected value; reach for decision-analysis mode when you want the numbers folded back.