When it comes to digging for those elusive truffles, you'll probably need the assistance of good truffle dog. Similarly, when in the murky interior of a process improvement project, the root cause can be hard to find. Unfortunately, good root cause hunting dogs haven't yet been bred, so you'll have to resort to some detective work, of the CSI or Sherlock type, to sniff out what's causing your problem. René Descartes realised this way back in 1637, when he nearly said "I think, therefore I analyse".
If you have a preference for fish, you can always try the Ishikawa species, which can be a bit bony. If you prefer a more direct approach, be inquisitive and just ask "why?" five times. You'll no doubt hit some dead ends along the way but remember that correlation does not equal causation. You'll have to try a bit harder than that. Just because it rains the day after you've cleaned the car doesn't mean that you caused it to rain, even if it seems to happen every time. On the other hand, if it really does happen every single time, the Australian Bureau of Meteorology would like to talk to you.