...without categorization Pareto charts and Ishikawa diagrams do not exist.
for example, for the chemistry analyzer referred to above the top failures may be:
slide insert fail
slide eject fail
Whole Blood Separator spin failure
transport arm crash
these are unique problem statements is in the 'Kepner-Tregoe' form of object-defect. they are not broad categorizations of causes (or defects or failures) as the OP referred to.
As for the fishbone diagram I assume you are referring to the sue of man, material, machine, etc.? If so this doesn't bother me as I never use the fishbone diagram. This categorization is actually what makes the fishbone diagram so weak in Problem solving as it breaks the natural cause and effect chain.
