Imagine the following situation - you have an Incident, no workaround is available, no permanent solution, nothing. I know, it is a rare case, but it happens. Even 3rd level of support are unable to find solution. So, is the service/product dead? (no more, gone to meet its maker, joined the choir i...

There was a discussion on KPIs for Problem Management in this forum back in 2006.
https://itilcommunity.com/modules.ph ... opic&t=787
(not sure if the link works, but it was 6 or so pages back, topic 787). Lots of ideas there, maybe useful?
Good luck