The effectiveness of any tool is dependent on the user and method use. So is the case with the “Fishbone Diagram (FBD)” or “Cause and Effect Diagram (CED)”.
No tool can achieve anything not intended by the user of the tool. A tool can only provide different perspectives to the user to take a decision. It is very much possible for the user to junk the information the tool provides and go by his or her feeling. The “Fishbone Diagram” or “Cause and Effect Diagram” is no exception.
Misuse of a tool can also include erroneous use, which could be either a genuine error or an intended misuse.
Means to pre-conceived end - The most common misuse of the FBD is to doctor various bones so that all root causes that emerge are in line with decisions already taken. Logic can be thrown to the winds as each immediate and root cause are written so as to justify the decision.
Effects instead of causes - Another common mistake people can make is to reverse the plotting of causes as a hierarchy of effects. Rather than progress causes from the effect to the root cause, it progresses through subsequent effects.
Incorrect or inaccurate problem statement definition - A guess or an assumption is made when documenting the Problem Statement or Effect. Then with the effect itself not being very correct, of what quality can the supposed “Root Causes” be?
Too much of guess-work in the causes - While all proposed causes are to begin with atleast, potential causes, if too many causes are all out of guess work or out of assumptions without a validation plan, then the likelihood of the problem being solved is next to nothing.
Tracing back from the root cause - After reaching the root cause, by relentlessly questioning “Why?” a comfort syndrome results in picking up an immediate cause rather the root cause.
Using Solutions as Causes - To prepare a justification for investment in a solution, solutions end up getting prefixed by “Lack of”. Examples could be lack of automation, lack of maintenance support etc.
Giving up after identifying one Root cause - Either due to the excitement of having identified a root cause or due to sheer laziness, it is possible to forget the basic tenet that one problem may have multiple root causes.
Confusing correlation with causation - Mistaking certain commonalities in various instances of problem occurrence as the cause of the problem itself is another common error.
Working to a strict time deadline - While no activity can go on endlessly, it is not possible to brainstorm and think through all root causes in a hurry or when wanting to close the meeting within a particular time. Many staff who participate will take quite some time to warm up and by the time they are ready to contribute, the meeting is over.
Criticizing proposed root cause ideas - It takes free, unfettered thinking to arrive at all root causes. If the thought-process of the participants are stifled for any reason, the fish bone will not complete and thus not effective.
Holy cows - There are certain people or certain processes in the organization which are sacrosanct and cannot be touched, let alone be changed whatever be the consequences. Therefore, all root cause analyses stop at this point.
“Out of control” causes - To be on the safer side and not end up with responsibilities, it is best if the fishbone analysis is guided to causes not within the organisational control at all so that no one in the organisation is tasked with the responsibilities of implementing corrective action.
People related causes - Documenting clichéd people related causes like, “Human error” (Are animal errors possible?), “forgot” (Is the process so dependent on memory) will not help in resolving the problem.
Focusing on “Who” rather than “What” - A classical distraction is to focus on who is the root cause instead of what.