Finding the Root Cause - Which technique is better?

C

Chicoria

#71
I find 5-why very effective. But there is a flaw in using 5-why and it has to do with what "Why" question you ask. You can ask why all day to the last answer you get, and still get nowhere (like an annoying child asking why to anything you say) .

I have found that 5 why works best with two other tools.
1. Having an understanding of how the system should work ideally. If you understand this you will ask questions as to why there was a departure from the ideal.

2. Gathering data between why questions to determine the exact departure from the ideal. I never ask a why question unless it is based on a departure from the ideal.

Example (a real one): A burr was missed at a milling op - found mid process by inspection and resulting in extensive rework. The GM wants the miller fired for causing rework.

Wrong way to use 5-why:

Q. Why did the operator miss the burr?
A. The operator didn't look for it.
Q. Why didn't the operator look?
A. The operator never looks for that burr, It never happened before.
Q. Why didn't it happen before?
A. I don't know.
Q. Why don't you know?
A. If I know that then I would know and I don't know. (This leaves you at a dead end - to continue asking why would be silly.


Better way:

Q. Why did the operator miss the burr?
A. The operator didn't look for it.
(You think: the operator should be looking for it in an ideal situation this is a departure from the ideal. So it is time to get some more data before you ask the next why
Q. Was the operator trained to look for it? (This is a set up for the next why.)
A. No.
Q. (You find the person who trained the operator.) Why wasn't the operator trained to check for that burr?
A. We never had that burr be a problem before.
Q. (get more data) But shouldn't the operator be trained to visual the part? Was that part of the training?
A. Yes, but it's a small burr and the next op is burring and it should have been taken off there where they have better tools.
(You now get more data from Burring)
Q. Why didn't you remove that burr?
A. I never remove that burr, quality has always accepted it.
(Now this is really strange. More data needed. You go see quality. As it turned out a new inspector was on the job and rejected the small burr that had never been rejected before. The normal inspector explains - we don't reject this burr because it goes to shop peen next and that takes the burr off. When it comes back it is in spec.
Q. (You think this would not have happened if it were documented - departure from ideal. So you ask) Was this ever documented?
A. I guess not.
Q. Why didn't you document it?
A. You can't document everything
Q. Did anyone ever train you on documenting with "key points"?
Miller not fired. Training on TWI "key points" Check found this was generally not understood in inspection so general training done. Follow up for next few months to see that key points are being noted by inspection. Key points being added to Op sheets as they come up for use.

At this point it is also a good idea to go back and check to see that each departure from the ideal is fully explained by the root cause you found. Sometimes there are more than one root causes. In this case you might check into what was going on that the burr hand let a burr go without knowing why it was okay.
 
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J

JaneB

#72
Knowing or rather, finding, the right Why? Questions to ask is critical to the success of the 5-why technique.
The technique can look or sound deceptively simple. It is anything but, if it is practiced and done well. And it requires effort and practice to do well. The more you practice at it, the better you get. It also helps a lot to learn for or with someone else who is skilled with the technique.

The question 'why didn't it happen before' might be a productive question in some situations, but it doesn't sound as though your exampl e is one of them. Does it actually matter that this hasnt happened before, for example? or is it of greater importance that it wasnt spotted? my vote is for the latter.
And 'why don't you know that' is silly, not to say unproductive. How would that help solve the problem?

It isn't just a matter of whizzing quickly through any 5 questions, all at the same time. It IS a matter of working out what are useful (productive) questions to ask, then asking the first. finding the answer to that, and thinking about the answer before you decide what is the next question to ask. And so on.

Your second example is a good illustration of the technique in action.
 

Jim Wynne

Super Moderator
#73
<snip>Better way:
Q. Why did the operator miss the burr?
A. The operator didn't look for it.
(You think: the operator should be looking for it in an ideal situation this is a departure from the ideal. So it is time to get some more data before you ask the next why
Q. Was the operator trained to look for it? (This is a set up for the next why.)
A. No.
Q. (You find the person who trained the operator.) Why wasn't the operator trained to check for that burr?
A. We never had that burr be a problem before.
Q. (get more data) But shouldn't the operator be trained to visual the part? Was that part of the training?
A. Yes, but it's a small burr and the next op is burring and it should have been taken off there where they have better tools.
(You now get more data from Burring)
Q. Why didn't you remove that burr?
A. I never remove that burr, quality has always accepted it.
(Now this is really strange. More data needed. You go see quality. As it turned out a new inspector was on the job and rejected the small burr that had never been rejected before. The normal inspector explains - we don't reject this burr because it goes to shop peen next and that takes the burr off. When it comes back it is in spec.
Q. (You think this would not have happened if it were documented - departure from ideal. So you ask) Was this ever documented?
A. I guess not.
Q. Why didn't you document it?
A. You can't document everything
Q. Did anyone ever train you on documenting with "key points"?
Miller not fired. Training on TWI "key points" Check found this was generally not understood in inspection so general training done. Follow up for next few months to see that key points are being noted by inspection. Key points being added to Op sheets as they come up for use.

At this point it is also a good idea to go back and check to see that each departure from the ideal is fully explained by the root cause you found. Sometimes there are more than one root causes. In this case you might check into what was going on that the burr hand let a burr go without knowing why it was okay.
The first thing you need to do, imo, is have a clear understanding of the problem. In this case, the initial question isn't "Why did the operator miss the burr?", it's "Why is this burr being created?" The presence of the burr is the actual problem.

Because there's a "burring" (assumed to mean deburring) operation, it appears that the presence of burrs was anticipated and perhaps inevitable, although it's not really clear because the initial finger was pointed at the milling operation. Why is there a deburring operation if the milling operation is expected to produce burr-free parts?

Given that there is a deburring operation, one should be able to assume that the mission of the operation is to remove burrs. In this case, a burr wasn't removed. Is the expected surface condition of the part, post-deburring, defined? Why would a deburring operator assume that some burrs are OK and others not, or that she shouldn't be checking the part for burrs of any kind or size?

I don't think much of the five-whys business because it's not really a problem-solving strategy. It's a way to demonstrate to a skeptical customer that RCA has been conscientiously done, and there's evidence that the cause has actually been identified and eliminated or neutralized.

Here's the deal: We all have things that we're good at and things we're not good at. Some of the latter variety can be remedied by training and experience and some can't. There are people who have good analytical thinking and problem-solving skills, and that's one thing that for the most part can't taught or learned. You either have it or you don't. To the extent that learning is possible, an exercise like five-whys isn't going to be helpful because a good analytical thinker follows a logical path to the answer anyway. What is helpful is experience with processes and knowing in a general way why and how things happen.

If you have people who actually need a five-whys form and exercise in order to solve problems, it means you have people who aren't well-suited to problem solving. Whyis that?
 

Stijloor

Staff member
Super Moderator
#74
Some managers really like the Why-Why method. They have a vending machine mindset. Drop a (too often very poorly defined) problem in, ask "Why" five ;) times, and out drops the root cause. :frust: :frust:

I am not bashing the Why-Why method; in some cases it can help folks getting closer to the root causes. It's the way it is (ab)used.

The biggest issues with any problem solving approaches are:
  • The problem/issue/nonconformity, etc., is very poorly defined.
  • Very poor root cause analysis. The so-called root causes are mere symptoms rather then real root causes.
  • Too often the process is punitive in nature, rather than a process that helps the organization improve.
  • The process is too cumbersome/bureaucratic.

"Lean" applies to this process too!! :agree1:
 
J

JaneB

#75
Ah Jim, as so often, you bring your analytical and clear thinking mind to the issue and break it down well.

The first thing you need to do, imo, is have a clear understanding of the problem.
Absolutely agree.
In this case, the initial question isn't "Why did the operator miss the burr?", it's "Why is this burr being created?" The presence of the burr is the actual problem.
I missed that - shows my limited experience in the field of machining. And highlights why asking the right questions, starting from the beginning, is important.

I disagree with a couple of your other points though. I do think 5-whys can be a useful tool and that with some coaching and training it can be learned/taught. But yes, a logical/analytical mind is a pre-requisite.

If you have people who actually need a five-whys form and exercise in order to solve problems, it means you have people who aren't well-suited to problem solving. Whyis that?
Er, yes.
 
T

treesei

#76
I once heard an explanation to WHY many root cause analyses go around and around the symptoms: If you dig deeper and deeper (assuming to the right direction), the final finger would point to the management incompetency. So let's just patch the hole and shut up.
 
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Miner

Forum Moderator
Staff member
Admin
#77
I am not a big fan of 5 Why for some of the reasons stated. Namely, It presumes that there is pre-existing technical knowledge that can answer the question, or that the practitioner will perform an investigation rather than simply guess. Most 5 Whys break down when the investigators guess without verifying.

It can be improved by breaking it out into three separate tracks:

  • Track 1: Why did the problem occur? Why was the burr formed?
  • Track 2: Having been formed, why did the control methods (or lack thereof) allow it to escape?
  • Track 3: Why did the QMS allow the root causes of Tracks 1 and 2 occur? This track is for Prevention purposes.
 
J

JaneB

#78
Good call, Miner, and good avenues to pursue.

To my mind, it ultimately matters little whether one calls it 5-whys or anything else... in the end, effective problem solving always comes back to asking the right questions, keeping on until you find something that looks logical and actionable, doing something along those lines, and studyng the results..

Treesei, while I can understand that cynical viewpoint, it's stopping at blame: let's blame management. It's supposed to be about management systems, not people. More effective to sheet the cause home to where it actually belongs, ie, something wrong in the management system rather than aiming at 'management'. And you might - might - get some management buy-in with that approach. Certainly won't with the former.
 

somashekar

Staff member
Super Moderator
#79
I once heard an explanation to WHY many root cause analyses go around and around the symptoms: If you dig deeper and deeper (assuming to the right direction), the final finger would point to the management incompetency. So let's just patch the hole and shut up.
I cannot say that I do not disagree with you ....
But, can we try to be a part of the solution rather than be a victim of the problem ...
There is no one best way for doing anything. The need is to work around and find the technical solution and / or system solution to a faced problem, within the environment.
Clear definition of the problem situation gets you to the clear root cause
Think Clarity, Sincerity towards the purpose of solution to the defined problem.
More than half the problem is solved if you now tread the path of the 5 why or any questioning.
5 why and such other methods discussed are therefore the tools in problem solving, and not the technique in itself.
 
C

Chicoria

#80
@Jim Wynne Don't you think that in nearly all initial situations the problem is not clearly defined? To simply say first you must define the problem is true but nearly impossible to achieve at the onset.

The first thing you need to do, imo, is have a clear understanding of the problem. In this case, the initial question isn't "Why did the operator miss the burr?", it's "Why is this burr being created?" The presence of the burr is the actual problem.
I think you are oversimplifying. The problem and second why finding example I gave you is a real one. Milling is milling and does only a brief deburr. The reason for asking why the burr was missed is because if it were found then the assumption is that the tool setting that caused it would have been corrected by the miller. After some questions the real problem was found in inspection. But to get from "Fire the Miller." to that clear understanding of the problem you have to ask some questions.

Because there's a "burring" (assumed to mean deburring) operation, it appears that the presence of burrs was anticipated and perhaps inevitable, although it's not really clear because the initial finger was pointed at the milling operation. Why is there a deburring operation if the milling operation is expected to produce burr-free parts?
Typical of situations that are often presented to quality, someone has already decided what the problem and the solution is. In this case an executive had decided it was the miller and the solution was termination. Fortunately a higher Exec wanted the root cause found before shooting from the hip. In such a situation it is best to start with the miller since she was under attack and the exec reading the result of the root cause analysis would want to know why she wasn't fired. You could say that part of the problem was the overly hasty suggestions from a mid level exec.

In my experience when you get a clear understanding of the problem the root cause(s) fall in place. Problems are not so much "solved" as uncovered. It would be wonderful if the "problem" you are presented with initially were the real problem. It seldom is. Once a clear understanding of the problem is achieved you are pretty much there with your root cause. So intelligently asking why, and comparing the answers to "the ideal" is a successful way to "resolve" rather than "solve" a problem. The Executive had "solved" it already - fire the miller. But that would only have lead to more problems. Finding what the problem actually is usually comes at the end of the root cause analysis. In this case it was an incorrect interpretation of what is acceptable at that point for in-process inspection, and not the burr. But initially there was no way to know that.

JaneB I quite agree with just about everything you say. You are an advocate of using intelligence and judgment as you apply the quality tools. I have never agreed with the view that the a perfect root cause system should be able to find the root cause no matter how stupidly it is applied. The effort to make such a system is admirable and should be done but it will never occur. As humans we have judgment and high intelligence. That is what separates us from the lower animals. We should use it as we apply our tools, not rely on them to do the work for us.

The simple instruction - just ask why 5 times - seems to assume a magic formula that will do the thinking for you. I think that is why many practitioners do not like it. What I am saying is that applied intelligently it can be very effective.

Using "Why questions" is a heuristic technique and in the right circumstance it is a very effective and fast way to get to a root cause, if it is done as I described it. Much faster, in most cases you run into on the shop floor, than fish-bone which can take weeks - months. But, as you say, Miner, when you are going into unknown technical territory, it is not the right tool. In such cased fish-bone is a better one. "Why questioning" is better when the correct process has already been laid out and there has been a departure from it. Perhaps that is a partial answer to the first poster's question.
 
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