I finished reading the book on six sigma quality control and stretched on my bed. Several things were going through my mind at the moment. For some unknown reason I was thinking about an incident that had happened about 10 years back. That day I had forgotten my railway pass and I was caught by a ticket checker. I had to pay the fine. I felt disturbed and I was cursing myself. How could I forget wallet. Why am I not more careful?
And then something flashed in my head. I sat up, took a pen and paper, and started calculating.
I traveled by train for nearly 12 years including my college years. Several times I had to travel by multiple trains or buses on the same day. And of course there were days when I sat home and did not travel. But I worked in a company that followed six days workweek. Also before I started regular train commute, I did a lot of train riding when I was kid, going to relatives, going to special competitions etc. So I traveled on most of the days of those 12 years, say nearly 10 years, that is 365 x 10 = 3650 days. Pretty much each of those travels was two ways, so that means 3650 x 2 = 7300 train rides.
If traveling in a train is a process, and if forgetting the ticket is a defect, then I had 7300 defect opportunities. Out of that I forgot the ticket only for may be two- three times. My defect rate is 2 defects per 7300. Using the calculator on following website
my process yield (successful completion) is about 99.97% and quality of my process is about 5 sigma. This is excellent process quality. Many manufacturing companies would die for achieving 5 sigma process quality.
But still it bothered me when I forgot the pass. Why? I was expecting myself to never forget. I was expecting zero defects. That is infinite sigma quality. The first rule in quality control and improvement is “Do not set unachievable targets”, which is exactly I was violating.
I needed to set my expectations correctly. I needed to keep room for myself to make some mistakes in reasonable limits.
If I extend this principle of “Quality of process” vs “Quality of expectations” in other areas, I get very surprising answers.
Mother does most of the cooking in house. Everyday for last several years she is cooking about 20 chapaties, rise, vegetable and curry. Making chapaties consist of getting right ingredients, mixing them in right proportions, kneading the dough, spreading the chapati using pin, baking it, putting oil on it and storing it properly so that it does not become dry and hard. Each of these steps is a potential defect opportunity. And this is just chapati making.
So overall making four to five food items is a complex process involving more than 50 defect opportunities per day. Make it twice a day and throw in several other defect opportunities for breakfast, tea, snacks and mom is managing a complex process called “feeding the family”, which has about 200 defect opportunities, that is potential to go wrong at about 200 places, every day. If curry has a bit more salt or chapaties are hard and dry, the family members will make a big deal about it and mom will have a bad day.
So, in 30 years of mom’s married life so far, the number of defect oportunities is 200 x 365 x 30 = staggering 2.19 million. Complexity wise, the process mom managed is similar to manufacturing process of a small item , say ball pen. By industry standards, if the ball pen maker achieves about 4 sigma process quality, that is considered excellent. For 2.19 million defect opportunities that amounts to about 15000 defects in pens.
Over the course of 30 years if a family were to allow mom 15000 cooking defects, that comes to about 1.5 defect per day.
So that means mom is allowed to screw up one small item every day.
Hah! can you imagine what would happen if mom made one cooking mistake every day? The family members will raise hell. Rather the expected standard for cooking is …
We don’t really allow lot of mistakes to mother. Even if she is cooking flawlessly for 10 years, and if on the 1st day of 11th year the curry is salty, and your dad is really hungry, there will be a hot argument. No matter what overall quality she has delivered for last 10 years, her performance is downed if she makes a mistake when WE ARE HUNGRY. Not fair.
In reality say moms make one mistake a month, then in 30 years she is making 30 x 12 = 360 mistakes. Over 2.19 million defect opportunities, it comes to impressive 5.14 sigma quality achievement. In QA terms that is considered passing with flying colors, A+ grade.
But again quality of our expectation is ?? zero defects per infinite defect opportunities, i.e. infinite Sigma. We ideally want mother to never make mistake.
This is problem with quality of our expectations. We keep the same super lofty expectations from ourselves and others. Instead we need to allow some defects in our everyday life. We need to keep some space for things going wrong. Things will always go wrong at some point. That is the reality. Out of 20 people we meet, one is bound to drive us crazy. Out of 100 things we buy, 2 will always turn out to be not what we expected. Out of 3 years in your life, you are bound to be sick for a week.
Quality should not be measured on the amount of disappointment we feel at the moment. It should be measured based upon the consistency over long term.
If we apply the same logic to trains being late vs. total trains running, or to power outage hours to total power available hours, we will find interesting results.
This reminds me of a story of Buddha. One day one man came to him and read a huge list of problems and complaints, complaint about hood children, nagging wife, lazy brother in law, harassing creditors etc. etc. He counted total problems, they were 83. Then he said to Buddha “please help me with my 83 problems.”
Buddha smiled and told him “I can’t help you with these 83 problems, but I will help you with your 84th problem.”
Bewildered, the man said “But I don’t have 84th problem”.
“You do.” said Buddha.”You are expecting not to have these 83 problems.”
Moral of the story – I must keep space in my life for things to to wrong. And if I think quality of my life is not so good, I need to recheck quality of my expectations.
Filed under: Engineering, Life, Mathematics, Quality, Six Sigma | Tagged: 6 sigma, buddha, Buddhism, Cooking, defects, fault tolerance, improvement, Life, mother, patience, process, Quality, Six Sigma |