> It's very hard to count things that don't happen
Interesting problem.
Just thinking about this particular issue, maybe some options are:
1) counting time and then expressing success as the longest period of time during which the bad events didn't happen,
2) letting it happen initially to have a base "bad rate", then taking action to bring that rate down, and continuously make an effort to keep the occurring rate down
People preventing accidents at industrial sites have good experience doing this.
Interesting problem.
Just thinking about this particular issue, maybe some options are:
1) counting time and then expressing success as the longest period of time during which the bad events didn't happen,
2) letting it happen initially to have a base "bad rate", then taking action to bring that rate down, and continuously make an effort to keep the occurring rate down
People preventing accidents at industrial sites have good experience doing this.