Bus factor

In business management, and especially in the field of software development, the bus factor is a measurement of the concentration of information in individual team members. It is also known as the lottery factor, truck factor, bus/truck number or lorry factor and connotes the number of team members that can be unexpectedly lost from a project ("hit by a bus", as it were) before the project collapses due to lack of knowledgeable or competent personnel.