Work out expected monetary value instantly with clear inputs, formula shown and shareable results.
Expected monetary value weights each outcome by its probability and nets off certain costs. The most decision-useful output is the break-even probability: the success chance at which EMV turns positive, because arguing about that single number is far more productive than arguing about the whole model.
EMV
EMV = P(success) x Upside - P(failure) x Downside - Upfront cost
Break-even probability
P* = (Downside + Upfront cost) / (Upside + Downside)
Only if you can absorb the downside. EMV assumes you can repeat the bet many times; a single ruinous loss is not compensated by a favourable average.
Base rates from comparable past decisions are far more reliable than expert intuition. Calibrate against history where you can.