This post provides my responses to each of the five questions that were posed in “The Fishbone Game“. If you have not played the game yet, please proceed to play the game at https://benchmarksixsigma.com/blog/let-us-play-fishbone-game/, and revisit this post with your answers ready.
Question 1 – X is an identified cause for Y and Y is a negative undesirable effect. Is the following statement True or False? –
It is possible that X is neither necessary nor sufficient for Y to occur.
My response is – TRUE (matches approximately 57% of responses)
Let us consider an example of Sudden Cardiac Death (SCD)- Some of the great athletes maintaining very good general health have died due to SCD, which happens due to sudden cardiac arrest (SCA), a medical condition that can lead to death within an hour.
The most common reason cited for SCA is the coronary artery disease (CAD). However, presence of CAD is neither necessary nor sufficient for the occurrence of SCA. Continuing further with the why – why analysis, the reasons for CAD are quoted as the following (source – bostonscientific.com)
- A family history of coronary heart disease
- High blood pressure
- High cholesterol
- Obesity
- Diabetes
- Sedentary lifestyle
- Smoking
- Excessive alcohol intake
- Age
Although, these are known causes, none of these individually or as a combination is a necessary condition for CAD. Also, none of these or any specific combination of these guarantees CAD. In this case, cause(s) is/are neither necessary nor sufficient for the occurrence of CAD.
Question 2 – X is an identified cause for Y and Y is a negative undesirable effect. Is the following statement True or False? –
In the quest to permanently eliminate Y, if X is found to be sufficient for occurrence of Y, we should consider just X as our focus area; X being necessary does not really matter.
My response is – FALSE (matches approximately 52% of responses)
The image above gives one example where the cause of call drop is sufficient but not necessary. Moving to a no-coverage area is a sufficient cause for a call drop.If we want to eliminate call drops, ensuring that user will not move to no-coverage area is by no means a complete solution.
Question 3 – X is an identified cause for Y and Y is a negative undesirable effect. Is the following statement True or False? –
If X is found to be sufficient for occurrence of Y, it means that X must also be necessary for Y.
My response is – FALSE (matches approximately 53% of responses)
The figure and explanation provided for question #2 is sufficient but not necessary to provide a response for question #3. 🙂
While ringing of a fire alarm is sufficient to create mass distraction at office work, it is not necessary for such widespread distraction. There are many more causes that can create mass distraction. Some examples are shown in the above image.
Question 4 – X is an identified cause for Y and Y is a negative undesirable effect. Is the following statement True or False? –
If X is necessary for Y, this means that the occurrence of Y is sufficient to prove that X has happened.
My response is – TRUE (matches approximately 63% of responses)
Another example – Switching a source of music “ON” is necessary for a person to listen to it. If a person is listening to music, this is sufficient to prove that some source of music has been switched “ON” by someone, somewhere.
Question 5 – X is an identified cause for Y and Y is a negative undesirable effect. Is the following statement True or False? –
To permanently eliminate Y, the following must happen – We must be able to target and address a set of X’s, which is necessary as well as sufficient for Y to occur.
My response is – TRUE (matches approximately 87% of responses)
In the above example, the following set of conditions are necessary and sufficient for inconsistency in gender and salutation.
- The user selects one field correctly.
- The user selects the other field incorrectly.
Jointly, these are necessary as well as sufficient for inconsistency to happen. In this example, there is an opportunity to eliminate inconsistency as the condition is actionable.
In this FISHBONE GAME so far, it is heartening to note that in all questions, the majority has matched my responses, although the margins are slender for questions 2 and 3. I invite you to comment and share your thoughts. Please use this link to comment.
Benchmark Six Sigma conducts workshops related to problem solving and decision making all across India and partners with a limited number of companies each year on "build your transformation team" projects. Public Workshops calendar can be seen here - http://www.benchmarksixsigma.com/calendar
Linkedin Group - To ask your own questions or to participate in interesting questions already posed, you may join our Linkedin Group - Lean Six Sigma War Room.
- When Design for Six Sigma Fails - September 24, 2015
- The root cause is missing - July 15, 2014
- Process Excellence Vs. Human Psychology - June 11, 2014
Good one, VK. Thanks.
Is it possible that one can check what were their original responses?
Notwithstanding, please append each game/exercise with such explanations as it makes the game all the more interesting to play.
I’m glad to be part of the community.
Regards,
hmmm. Thanks for bringing this up. The situation we have this – The current platform does not support recording individual responses and even if we find a way, people shall have to login before playing the game which is a deterrent for some. I have raised this internally and we shall explore more in this area in times to come.
Hi VK
This was interesting….but in my experience with service industry, I have never come across such a dilemma where in I had to think whether this cause is necessary and/or sufficient for the effect.
It will help if you have any business related examples to further explain how this could be used while doing RCAs or Fishbone Analysis. One e.g. which I can give is – a defect is an undesirable effect. A common cause which we usually get is that the process step is not mentioned in the SOP. But when we check it with other team members they say they knew about the update and hence did not commit the same error. So in this case my X is neither necessary nor sufficient for Y.
Also, taking this entire exercise a step further…..what should be the priority for solutions? X which is necessary, X which is sufficient or X which is both? Cause in the above example, we still go ahead and update the SOP 🙂
Hi Mayank, I appreciate your deep thought in the subject and I am glad your raised this question. With respect to business application, these concepts are very useful in RCA when you wish to completely eliminate the occurrence of Y which is a result of many factors or when you decide that a process is worthy of FMEA. While carrying out detailed FMEA with a team for a complex process and making a list of factors that can go wrong, you will notice that this kind of discussion actually happens. IN the chain of cause -> failure mode -> effect, the does utilize concepts of sufficiency as well as necessity in different contexts. In FMEA, the same concept is likely to be discussed in a different way for existing process controls and for the recommended process controls. As this does need deeper thinking, I am thinking of a thought inducing format to run a contest on this subject some time later. Hope this helps.
the analysis n exercise was good n pictures made it interesting, thanks VK.
You are most welcome, Rakhee.
Dear VK,
The examples shared has made things very clear.
However in example 2, the requirement is to avoid calls. So call drop cannot be a negative undesirable effect. The example I think needs to be revisited in this case. Thanks.
Hi Tharani, thanks for your comment and participation. Being in this domain, you know this field more than me and you are absolutely right. The example presented in lighter vein shows that objective from the recipient perspective is call avoidance. In that sense this a dual example – 1. People may misuse a situation from their personal perspective. The example makes sense from the telecom operator’s point of view as well – If the operator wants to ensure that call drops be prevented completely, it cannot afford to consider reasons that fall only under the sufficient category. I completely agree that the focus should have been more on the operator side and probably I got a bit carried away in my effort this time. Thanks again.
Hi VK, Sorry for being late !
Just one dilemma. If X is a necessary condition then can there be any other X too which is necessary?
From the explanations given before the game – Necessary means – you address X and Y will be addressed – guaranteed!!
Hi Neeraj, good to see your comment here. if X1 (one cause) is a necessary condition, there can be another X2 (another cause) which is necessary as well. As an example, there are several inputs each of which is necessary for a plant to create its food through photosynthesis.