The Mystery of Missing Advent Calendar Chocolates:


It is Christmas time, which means it is advent calendar time for the kids and for those of us who are kids at heart. My wife bought our kids chocolate advent calendars from Trader Joe’s. For those who do not know advent calendars, these are countdown calendars to Christmas starting on December 1st. Each day has a window which you can open to reveal a chocolate. Each day has a uniquely shaped chocolate, a Christmas tree, a stocking etc. The kids love this.

We keep the advent calendars on the top of our refrigerator to ensure they are not tempted to eat all of the chocolate at once. This morning, I found the advent calendars on the table and a crying Annie. Annie is our youngest daughter. She was very upset.

“I did not get any chocolate today from my calendar”, she said while crying.

“You must have eaten it already”, was my response. Of course, the kids eat chocolate and sometimes they are impatient and eat more than one day’s worth. In my mind, it was a reasonable assumption to make.

Annie explained that she opened the window with 6 on it and did not find any chocolate. I looked at the calendar, and sure enough, the window for day 6 on it was open. My initial hypothesis stayed the same – Annie ate the chocolate, and she is not telling me the entire truth.

My wife suggested she open the window for day 7 and eat that chocolate. Annie then proceeded to open the window with 7 on it, in front of me. Lo and behold, it did not have any chocolate. Annie looked at me with sad eyes. I realized, I was wrong to have assumed that Annie had eaten the chocolate!

“This is a mystery”, said Audrey, her twin sister.

Now I had a second hypothesis – those darn calendar makers; they do not know what they are doing. They obviously missed filling all the spots with chocolate. As a Quality Engineer, I have seen operator errors. I have now jumped to my second hypothesis.

Having thought about for a bit, I looked at the available information. Based on what Annie told me, the chocolate was not in its spot for two consecutive days. These calendars did not have the numbers in the consecutive order. They were placed in random order. It did not strike to me that two candies at different locations would be missing candy. She had opened a spot between 6 and 7 on an earlier day, and it had the candy.

I had a reasonable hypothesis – the operator/equipment missed the spots in the calendar. I have seen it happen before in different environments. But still, something was not right.

I proceeded to put the advent calendar back onto the top of the refrigerator. Then I thought of something. I wanted to test the calendar more. I carefully opened the calendar from the base. It was a card board box with a plastic tray inside.

Just then I found out what happened! On multiple places, the chocolate was missing. The chocolate were misplaced from its cavities. They were all gathered at the bottom of the box. It could be from the transportation. It could be the end user i.e. my excited young daughter who shook the calendar. It could be the design of the calendar that allows extra space between the tray and the cardboard.

The most important thing was that Annie was now happy that she got her candies. Audrey was happy that we indeed had a mystery that we could solve. My wife and I were happy that our kids were happy.

Final Words:

This personal story has made me realize again that we should not jump to conclusions. Listen to that tiny little voice that says “there is something more to this”…

Always keep on learning…

In case you missed it, my last post was about “Lady Tasting Tea”.

Is Murphy’s Law alive and well?


In today’s post, I will be trying to look into Murphy’s Law.

There are multiple versions existing for this law, the most common version being – “whatever can go wrong will go wrong”. Some other variations are as follows;

  • If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.
  • If everything seems to be going well, you have obviously overlooked something.
  • Nature always sides with the hidden flaw.

Murphy’s Law makes a pessimist out of the most optimistic man. Is it true that the universe has a tendency for causing things to fail? Does Murphy make a rational man go “Why me?”, when something unexpected happens?

A common version of Murphy’s law is the case of buttered toast. The buttered toast always fall on the buttered side. Let’s look into this deeper.

Does buttered toast listen to Murphy?

The following section is taken from “The Australian Journal: A Weekly Record of Literature, Science, and Art, Volume 23”, from 1888. The highlighted section shows that the idea of buttered toast/bread falling on its buttered side is common, even in the 1800’s.


Interestingly, studies have shown that buttered toasts fall on their buttered side almost 62% of the time. This would mean that it is not a fifty-fifty chance like flipping a coin. Why? This seemingly curious “bad luck” can be explained with science. Delving deep into the case of buttered toast, it becomes clear that the following factors always remain the same;

  • The toast always starts with the buttered side face-up
  • The height of the fall is similar (2-3 feet). This is because the toast is held at waist height generally, and in the case of falling from a table, the standard table height is between 2-3 feet.

These two factors increase the chances for the toast to fall on the buttered side. In fact, studies have shown that when toasts are thrown up in the air, the likelihood decreases to fifty-fifty. Alternately, when the toast is dropped from a height of 7-8 feet, the likelihood of buttered toast falling on the unbuttered side goes up back to about 62%. The reader can find more about this here and here.

Does Murphy still seem threatening?

Factors which cause Murphy to visit:

I have compiled a list that explains why Murphy is prevailing.

  • Nature of humans: Humans always remember when something bad happens to them. Do you remember the last time your car broke down and you had to call for it to be towed away? Do you remember the other 99.9% of time, where you did not have any problems with the car? Since your brain likes to avoid making mistakes, it likes to recall the bad times more so that you do not repeat the same mistakes. The downside of this is that it can make you start noticing only the bad events. Think of a large white paper with a small black dot. Our attention is on the black dot, and not at the remaining 99.9% of the white space.
  • Law of large numbers: The bad thing about events with relatively small probabilities is that they will still happen. No matter how small the probability, with enough chances the event will happen. The probability of winning the powerball lottery is 1 in 292,201,338. Even with such a small probability, people still win the lottery on a regular basis. The probability of somebody winning a lottery goes up when the prize gets really high (>$300 Million). This is because, a larger amount of tickets are sold during that time. As Law of large numbers dictates, with enough chances even the low probability event of winning a lottery happens.

Combining the Nature of Humans, and the Law of large numbers, you have the perfect storm that allows Murphy to rule the world. The egocentric view of humans tends to make events about them, when from a probability standpoint, it could have happened to anybody. There is a profound difference between asking “What are the chances of it happening” and “What are the chances of it happening to me?”

  • Law of Nature: It is the law of nature that everything degrades over time. Eventually, all products will fail. A good example is when you move into a new house, and after about 7 years, more than one appliance starts to breakdown. First it was the refrigerator, and now it is your washer as well. The fact that the two appliances were bought together might escape your mind, and you will blame Murphy.
  • Poor Processes: In relation to item 3 discussed above, if you have poor processes, the chance of multiple things to fail goes up. A good example is poor preventive maintenance procedures. Multiple equipments can break down at the same time, if they are not maintained properly. If one equipment can go bad, there is a good likelihood for another to go bad at the same time, if the same poor preventive maintenance program was being used. A poorly designed system can become a playground for Murphy.
  • Special Causes: Sometimes the unlikely event(s) happens due to special causes. Sometimes this special cause can be an enabling condition that allows multiple things to breakdown. The special cause at times is people. People are inherently inconsistent, and they can add inadvertent variation to the process that makes thing go wrong.
  • Complexity and Chaos: Murphy’s law is very much relevant in the presence of complexity and chaos. In the presence of disorder and uncertainty, the reliability of a system can breakdown easily. Any order from constraints is disrupted and this allows more things to go wrong. I welcome the reader to visit Cognitive Edge website to learn more about this.

Final Words and the story of Arthur Ashe:

As detailed in the buttered toast section, it is imperative that one tries to understand why something went wrong. What are the factors affecting the process? What are the chances of the event to happen? Is there indeed a pattern or is the pattern created by the perception? The buttered toast is a rigged game where there is high likelihood of the toast to fall on its buttered side when dropped from a height of 2-4 feet.


Arthur Ashe, the legendary Wimbledon player was dying of AIDS which he got due to infected blood he received during a heart surgery in 1983.

From the world over, he received letters from his fan, one of them conveyed: “Why does God have to select you for such a bad disease?”

To this Arthur Ashe replied: The world over–50,000,000 children start playing tennis, 5,000,000 learn to play tennis, 500,000 learn professional tennis, 50,000 come to the circuit, 5000 reach the grand slam, 50 reach Wimbledon, 4 to semi finals, 2 to finals. When I was the one holding the cup, I never asked god “Why me?”

And today in pain, I should not be asking GOD “why me?”

Always keep on learning…

Is Inspection Value Added?

pass fail

In popular Lean circles, the idea of value-added is represented by the following two criteria;

  • Is your customer willing to pay for the activity?
  • Is the activity physically changing the shape or character of the product so that it increases the product’s value in the eyes of the customer?

In lieu of these criteria, is inspection value added? Before answering, please be aware that this is a loaded question. Also understand that the question is not “should we inspect product?”

Inspection generally does not alter the physical attributes of a product. Inspection in the traditional sense accepts or rejects the product. In this aspect, inspection should prevent a bad product from reaching the hands of the customer. Does this mean that then the inspection activity is value added?

As a customer, I would love it if the product is inspected, and reinspected ten times. But I would not want to pay for such an activity. Are we as a society of consumers wrongfully trained to think that inspection somehow increases the quality of the product?

Deming’s view:

Dr. Deming’s view of inspection is as follows;

Cease dependence on inspection to achieve quality. Eliminate the need for inspection on a mass basis by building quality into the product in the first place.

In fact, this is the third principle of his 14 key principles for management to follow for significantly improving the effectiveness of a business or organization. Deming’s view is clearly stated in his “Out of Crisis” book. “Inspection does not improve the quality, nor guarantee quality. Inspection is too late. The quality, good or bad, is already in the product.”

Shigeo Shingo’s View:

Shigeo Shingo is considered by many a powerful force behind Toyota Production System. He trained Toyota employees with his “P-courses”. Shingo was the person behind Poka-yoke (Error proof) and SMED (Single Minute Exchange of Dies). In his views, there were three types of inspection:

  • Judgment Inspection – inspections that discover defects
  • Informative Inspection – inspections that reduce defects
  • Source Inspection – inspections that eliminate defects

Judgment inspection is an inspection that is performed after the fact. The lot is produced, and then inspection is performed to determine if the lot is acceptable or not. In Shingo’s words “It (Judgment Inspection) remains inherently a kind of postmortem inspection, however, for no matter how accurately and thoroughly it is performed, it can in no way contribute to lowering the defect rate in the plant itself.” Shingo continues to state that the Judgment Inspection method is consequently of no value, if one wants to bring down defect rates within plants.

Informative Inspection is an inspection that helps in reducing defects. This method feedbacks information to the work process involved, thus allowing actions to take place to correct the process. Shingo describes three types of Informative Inspections.

  1. Statistical Quality Control Systems – This is the system with control charts where one can identify trends or out of control processes, aiding in getting the process back to stability.
  2. Successive Check Systems – This is the system where the component gets inspected by the next operator in the line. Any defect is identified and corrected almost immediately by letting the previous operator know. Please note that ideally this system uses 100% inspection.
  3. Self-check systems – This is the system where the operator can inspect the work that he/she did, and fix the problem immediately. Please note that ideally this system uses 100% inspection.

The final category is Source Inspection. In this category, the feedback loop is so short that as soon as the error occurs, the feedback kicks in preventing the error from becoming a defect.

Feedback Loop – The Key:

The key in determining value in the inspection process is the length of the feedback loop. Judgmental Inspection is the least value adding in this regards because the product lot is already built and completed. Informative Inspection is value adding, since the feedback loop is considerably shorter. Finally, the source inspection is the most value adding since the feedback loop is the shortest.

The feedback loop is shown below.

feedback loop

Thus, the shorter the feedback loop, the higher the inspection method’s value.

Final Words:

This post started with a question, Is inspection value added? Errors are inevitable. Drifts in processes are inevitable. Learning from errors is also becoming inevitable. Inspection activities that increase the system’s value are definitely value added. I used to wonder, whether kaizen is value added. Is a customer willing to pay for an organization to be a learning organization? I came to the realization that kaizen is based on a long term principle. The real value is in cultivating the long term trustful relationship with the customer.

Inspection activities that allow the organization to grow and learn are definitely value added. The table below summarizes this post.


Always keep on learning…

Drop the PA from CAPA


The new revision of ISO 9001 is going to be released later this year. One of the changes proposed, that piqued my interest, was removal of the Preventive Action section. Preventive Action is “replaced” with Risk Based Thinking.

Preventive Action is proactive in nature. So is risk based thinking. Since my field is medical devices, risk based thinking is deeply engrained in me. It is my understanding that this revision is proposed to create a management system that is risk based.

One of the ways that I have used the PA of CAPA is to identify potential opportunities to implement what we learned from the CAPA. This could be similar products, processes or designs. This is similar to Yokoten in Lean Manufacturing. Jon Miller at Gemba Panterai calls this as “Horizontal Deployment”.

Yokoten means “horizontal deployment” and refers to the practice of copying good results of kaizen in one area to other areas.

The new revision does not take away this meaning. The new revision has in fact moved the thought of risk based thinking to Planning section. Thus, the intent is to spread the idea of risk based management throughout the organization.

As mentioned earlier, risk based thinking is proactive by definition. When properly done, risk based thinking can reduce the nonconformity occurrences, thus reducing the need for corrective actions. Corrective actions are reactive in nature. Risk based thinking leads to more preventive actions throughout the organization.

Paraphrasing heavily from the proposed changes;

When planning for QMS, the organization shall determine the risks and opportunities that need to be addressed to (among other things) prevent or reduce undesired effects.

It will be interesting to see how this will be handled with ISO 13485 standard.

Keep on learning…

8 Things I learned from Spock


Spock (Leonard Nimoy) is no more. The character of Spock from Star Trek has had a huge impact on many peoples’ lives. Leonard Nimoy will be deeply missed.

Here are 8 things that I learned from Spock.

1) If you do not have enough information, say that you do not have enough information or that your hypothesis is based on the limited information. As a Science Officer, he very well knew that he had to give the best possible opinion at all times. But he was open about his lack of information to form an effective hypothesis. For example, Spock would respond “I simply do not have enough data to form an opinion”, to Kirk’s “Opinion, Mr. Spock?” question. Kirk would then follow up with “Speculation, Mr. Spock.”.

2) Do not mix emotions with your hypothesis. In other words, try to eliminate or minimize confirmation bias. This was what separated Spock from Bones in the show.

3) Always have an open mind. Spock always remarked “Fascinating” anytime he came across something new. This also tells us to minimize our confirmation bias.

4) Look for patterns to form your hypothesis. After all, that is the role of a Science Officer.

5) Try to think rationally. Spock put a lot of emphasis on logic.

6) Always be abreast with the latest in your field. This was essential for Spock as a Science Officer. Always keep on learning.

7) Things are not always black and white. Spock learned this from Kirk. Kirk was always willing to challenge the status quo.

8) Improbable things can happen. As Spock said “It would be illogical to assume all conditions remain stable.” With enough iterations, even highly unlikely events can happen.

Thank you and Good Bye, dear Leonard Nimoy.

Keep on learning…

Understanding the void

As a data scientist or a quality professional, one should understand the whole picture. Sometimes this means that you have to gain information from what is there as well as what is not there. I like to call this the void.

A great story that comes to my mind regarding this is from a talk from Jeffrey S. Rosenthal. He also posted this in a great article called “I am biased, You are biased“.

” During World War II, the U.S. Air Force wanted to strategically reinforce the hull plating of its fighter planes to better withstand enemy fire — but which parts of the plane should be reinforced? Charts and graphs were carefully constructed, showing the location of bullet holes on returning aircraft. The military then decided to consult a statistician — always a clever move. Professor Abraham Wald immediately realised that those graphs were based on a biased sample: they only included data for the planes which actually returned from battle. The real issue was the location of bullet holes on the planes which were shot down and never made it home. The military wisely followed Wald’s advice, to reinforce those parts of the hull that came back clean and bullet-free — those were the places where any shots would be fatal”

Keep on learning…