True Root Cause

Ramesh,
The first ‘why’ should be used for the ‘failure mode’ identified and not the problem / symptom.
Example-
Problem/Symtom – You are late to reach office every Monday.
Failure mode- You wake up late in the morning.
1st why – You were awake till late night the previous night.
2nd why – You attended a party.
3rd why – You have it every Sunday.
4th why – Not reqd.
In the above example, you have seen that the root cause is ‘you have party on every Sunday’. So solution is to have it on Friday / Saturday evening instead of Sunday.
Whether you need 5 whys or more will depend on when do you ask the 1st why. Ask the 1st why to the failure mode and you should be able to reach the root cause in next 3-5 steps. Thats what experience says.
Monk

Whole concept of reaching to root cause through Why – Why Analysis (or any other tool) depends on two things:
(1) Each why should focus on causes of effect seen.
(2) Number of whys are determined based on our capability to ACT e.g. in the example quoted if you are able to sleep on time irrespective of anything..stop there while if you can not change party evening go further…..quality is about action (not analysis – paralysis)
Most important of all…why – why analysis is a simple tool used for solving simple problems (believe me it depends on experience as well). Some tools which use domain expertise and problem observations as inputs are experience based, while others which are data based are more deterministic. Six Sigma is mix of both types of tools

RCA stands  for  what? thanks

tHANK yOU

Ramesh,Regarding your note earlier today, where you commented “I thought six sigma is teachable science”.Six Sigma (or Lean, or TQM, or any other improvement methodology) is blend of science and practical experience.Improvement practitioners (Six Sigma, or Lean, or TQM, or any other improvement methodology) are like medical doctors.

The medical doctor, at a minimum, has to do these things to get certified (licensed):1. go to courses to understand the underlying knowledge of how the human body works (AND pass the exams);2. Follow senior doctors on their rounds, to understand how to apply this knowledge; and3. Practice applying the knowledge under the watchful eye of senior doctors.I would not feel comfortable working with a medical doctor who only went classes and read medical books and journals. I want my doctors to know medicine AND to have learned how to apply it under the watchful eyes of senior doctors.Six sigma practitioners (and Lean Masters, and our other improvement brethren) are the “doctors” in our organizations. I want my improvement “doctors” to:1. go to courses to understand the underlying knowledge of how the “organizational” body works and how to improve it, using Six Sigma, Lean, etc. (AND pass the exams);2. Follow senior Six Sigma practioners on their rounds, to understand how to apply this knowledge — this means being on some projects led by senior BBs or MBBs; and3. Practice applying the knowledge under the watchful eye of senior practitioners — actually do a Project, under the watchful eye of a MBB, or at least a senior BB.If you have read and studied about Six Sigma, Lean, etc., in books, that is only part of what is required. You will also need to practice Six Sigma. If new to Six Sigma, this should be done under the guidance of an experienced practitioner… hope this is helpful ….
Best regards,QualityColorado

Ramesh,
In Six Sigma, you need to do the 5why’s using the expertise of the CFT in that process. 5Why’s would only give you possible root causes and mind you that the answer of your 1st “Why” is not limited to one answer-you could have as many possible root causes in which you would use for your 2nd level “Why” until you reach the level five “Why.” (some might only be until 3rd level why.)
1st level       only one  Why1 (the main problem)
2nd level     Why2a, Why2b, Why2c,….
3rd level      Why3Aa, Why3Ab,….;Why3Ba, Why3Bb,….
etc.
The last answer of your Why’s could reach up to 20 possible root causes or more. You can use C & E matrix to reduce the possible root causes down to the most possible root cause-these are your x’s.
Now is the time to use the statistical tools, the remaining possible root causes will be evaluated using hypotheses tests or DOE depending on the type of data you can collect.
As a summary, 5why’s would only help you find the possible root causes, Hypotheses tests and DOE would help you find the root cause which are the significant factors that affect your main problem.
abetf
 
 

I’m ever bothered by topics such as this.  We are so focused on buzz that we overlook the simple factors that solve the problems.
Root cause is a waste of time unless you’re writting a book. Solving problems is the true focus – that’s what we are paid to do…
If you want a better toolbox, get rid of the fluffy buzz toys and go back to basic problem solving – 5 whys, 6, 7 or 100 – what difference – that’s only a linear story. Focus on solutions and solve those problems.

It is noted after the 7th why the person that is answering your “Y’s” starts becoming annoyed with you.  You can try that with someone

Teachable – yes, science – no.