Lottery Factor
Bus Factor
Aa measurement of the risk resulting from information and capabilities being lost or not being shared among team members. From the phrase, "in case they get hit by a bus."
Origin
The concept circulated in software engineering through the 1990s as "truck factor" and "bus factor" interchangeably — naming the minimum number of team members whose sudden loss would stall a project. James Coplien addressed related ideas in his work on organizational patterns from 1994, and the term "truck factor" was formally defined in Laurie Williams and Robert Kessler's 2002 book Pair Programming Illuminated. "Bus factor" became the dominant variant in agile and open-source communities, valued for the darkly humorous framing of a serious risk-management problem.