[thaumasiotes]

> when comparing bus factor of projects of different sizes [] it makes sense to normalize by dividing by the size of the team

Consider two projects, a one-man project with a bus factor of, obviously, 1, and a 100-man project with so much redundancy within the group that the bus factor is an impressively robust 50. The standard bus factor immediately tells us that the big project is much much less fragile.

The "normalized bus factor" you describe (1 for the solo project, 1/2 for the huge project) perversely tells us that the big project is much more fragile, in that it will be disabled by the loss of 50% of the team, while the solo project will only go down after a full 100% of the team is eliminated.

Why does it make more sense to count redundancy by "percentage of the team, whatever size the team might be" rather than by "number of setbacks before project failure"? In general, the bigger team really does make the project more robust, not less robust.