Start with the decision, not the proposal. Most investment cases arrive as answers: a site to open, a platform to buy, a business to acquire. The first question is what decision is actually being made and what alternatives were considered — including doing nothing. A proposal without alternatives is an advocacy document, not a decision.

Size the value at stake honestly. Ask what the investment is worth if it succeeds, what it costs if it fails, and how wide the range between those outcomes is. Many cases present a single point estimate with a confidence the underlying data cannot support. The width of the range tells you how much diligence the decision deserves.

Write down the assumptions that must hold. Every plan rests on a handful of beliefs about customers, competitors, costs and capability. Name them explicitly and ask which are evidence-based and which are hopes. The most dangerous assumptions are the ones everyone in the room shares without having checked.

Define what would make you stop. Agree in advance the signals that would indicate the plan is not working and what the organisation would do in response. Kill criteria set before commitment are far easier to honour than judgements made after money has been spent.

Agree who decides and who is accountable. Investments fail quietly when ownership is diffuse. A single accountable executive, a clear decision forum and a review cadence turn a case into a commitment.

None of these questions requires more data than most organisations already have. They require the discipline to pause before the momentum of a well-made case carries the room. In our experience, that pause is where most of the value of a major decision is created — or lost.