refers to the risk quantity identifying, of all the internal  knowledge critical to a technical team performing its functions,  what is the smallest subset of the team that is exclusively familiar  , with one of those knowledge choke points. In other words 😆, what is the minimum number of buses required to knock out members of the team such that no one of those left standing near the critical knowledge . 

Here is the pace analysis from a recent walk I did with a buddy . We went for a walk to IKEA then we walked around in IKEA. Then we grabbed some burgers 🍔. Then we walked to get some drinks . Then we got on a bus ! And the pace analysis reflects this walk had a bus factor of approximately 1.6/6.6 , that is the proportion of the miles ( or kilometers as my friend would say), that were of bus in origin .