ASQ Six Sigma Green Belt – Blockchain 101 Part 5

32. Objective – Bitcoin Improvement Protocols

Talk about this topic later on in section three F. Right now let’s have a quick introduction to what is process capability. So, let’s keep it simple. And let’s say you are manufacturing a shaft, a horizontal shaft of 1 meter length. Since everything has a variation, this length also will have variation. So you cannot produce 1 meter exactly every time. But for that you have some specification also. Specification is something which designers tell you that for this shaft to work, this is the range you need to make this shaft into. Let’s say the specification which you got was 100 CM plus -3 CM so let’s say this is something which you are required to produce. So this is your specification. So your specification says that you can make this sharp anything between 97 to 103.

But once you start producing this sharp, how much capable your process is. This is what this particular measurement does. Let’s say if you have created, let’s say 100 200 pieces of this sharp and you have seen that this follows a normal distribution. And let’s not go into the detail of normal distribution at this stage. Let’s say that you have found out that most of the times you are able to make this shaft in 99 to 101 only. That is very good because you were required to make it in plus minus three. But you were actually were able to make in plus minus one. What does this mean is that your process is three times more capable than it was required to be.

So having a factor of three means that you have a good chance that you will be able to produce this shaft within this specification. Even though something goes wrong, still you will be able to make this shaft. So this is what is the measurement here. CP or CPK tells that how much capable your process is. In this particular case, in this particular example, we had a process which is three times more capable. What we need in reality is your process should be capable to meet the specification. So CP or CPK is equal to one is just fine. It’s okay because you are meeting the requirement. But then there is fluctuation. So for that, most of the time we say that this should be 1. 33. So your process should be 1. 33 times more capable than what it was required to produce. We are not going into details of this at this moment. But this is all you needed to understand at this time, that the process capability indices these tell that how much capable your process is. And this gives you a ratio. Ratio of 1. 33 is good. Two, three, four. Much better.

33. BTC Explorer

In yellow belt, you would have understood that when we have a six sigma performance, that is equivalent to 3. 4 defects per million opportunities or DPMO. So six sigma is equal to 3. 4 DPMO. And this is what we are talking here. What DP M O is to understand defects per million opportunities. Let’s go step by step. Let’s first ask understand what does defect opportunities mean? Then we will talk about defects per opportunity. And then we will talk about defects per million opportunities. Let’s understand defect opportunities first. What does defect opportunities mean? Defect opportunities are circumstances in which the product or service can fail to meet the requirement. Now, this is a hypothetical number that in how many ways this item can fail can fail to meet the requirement. Let’s say I have this curtain boxes on my left. These curtain boxes I have to check and make sure that they are right. Now, as a company, we have identified that there are three opportunities of defect in each of these boxes. So whatever box we produce, this box can fail to meet the requirement in three ways. Let’s say one way would be that this size is not right.

The second thing would be let’s say the thickness has changed. The third thing would be there is no sticker or the identification on this box. Let’s hypothetically think that based on the history, based on the production we have done, we understand that this particular box can be rejected based on these three items. The size, the thickness or the label. So these are three opportunities. This particular product can fail. So these are defect opportunities. Now, when we talk of defect opportunities, if the product is simple such as this cutting box here, we have three defect opportunities. But instead of that, let’s say if we have a laptop or let’s even take, let’s say if we have a missile or let’s say if we have aircraft, there could be lots and lots of defect opportunities. So there are thousands and thousands of things which we can call as defects in an aircraft.

So things could fail in thousands and thousands of ways. So what you need to understand is you list down all those opportunities where these products can fail. And in case of simple products such as cartoon box, this number will be limited. In case of a bigger and a complex thing, this number will be much higher. So complex unit will have greater opportunities of defect as compared to the simple units. Now, how do we find out defect opportunities? We said that each box has three defect opportunities. Now, what we have is five boxes which came to inspection. Now, in these cases, how many defect opportunities are there? The answer is simple. Five boxes multiplied by three opportunities for each box is equal to 15 defect opportunities. So this is the first step in calculating DPMO or defects per million opportunities. The first thing is to consider what are the defect opportunities which we have done here.

So after talking about defect opportunities, let’s consider a case that these five boxes together form a one unit. If you have gone to Ikea, you bought a furniture, you would see that the furniture comes in number of boxes, box one of five, two of five, three or five. So five boxes together form one unit which goes out to the customer. Now, let’s assume that I am doing inspection and I get ten of these units for inspection. Ten units each having five boxes. That means I got 50 boxes to check. In these 50 boxes, let’s say I find out that there are two defects here and here I am talking about defects, not defectives. So these two defects could be in a single box or these two defects could be in two different boxes after having found out that I have two defects here.

Now, what are defects per opportunities? So defects per opportunity in this case will be two. Because two are number of defects divided by 15 multiplied by ten. Because we have talked earlier also that each box has three opportunities and five boxes together becomes one unit. So there are 15 defect opportunities in each of these units. And we have got ten such units. So 15 multiplied by ten will go in the denominator. So two divided by 150. So that will give me zero point 13 three. So this is my DPO or defects per opportunity. Now, after looking at defects per opportunity, the next thing will be to find out defects per million opportunities. And that we can do very easily by multiplying DPO by 1 million. So 0. 133 multiplied by 1 million gives me 13,333 as a DPMO. So this is how I calculate my DPMO or defects per million opportunities.

And if you remember, 3. 4 DPMO is equivalent to six sigma performance. So that I can say with very much confidence here that this particular production process is nowhere near six sigma performance. But then at what sigma performance level we are, let’s look at a chart first. And here I have a chart which shows the relationship between the sigma number and the DPMO or defects per million opportunities. So if you look here, six sigma is equivalent to 3. 4 defects per million opportunities. Four sigma means 6220 defects per million opportunities. So this is the table. This table tells me that six sigma is equal to 3. 4 DPMO. But then if I have 13,333 DPMO, then what is my sigma level? So that will be somewhere in between these 3. 5 and four. Somewhere here I will have 13,333 which is roughly equivalent to 3. 7 sigma. So by this process is at 3. 7 sigma level, not at six sigma.