The bus factor is a measurement of the risk resulting from information and capabilities not being shared among team members, from the phrase "in case they get hit by a bus". It is also known as the lottery factor, truck factor, bus/truck number or lorry factor. The concept is similar to the much older idea of key person risk, but considers the consequences of losing key technical experts, versus financial or managerial executives (who are theoretically replaceable at an insurable cost). Personnel must be both key and irreplaceable to contribute to the bus factor; losing a replaceable or non-key...