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The Seven Basic QC (Quality Control) Tools are a given set of graphical techniques identified as being helpful in troubleshooting issues related to quality[1]. These seven are called basic because they can be used easily by anyone to solve the vast majority of quality-related issues. Many quality professional believe these were originated by Dr. Ishikawa, a world renowned quality professional. But, he would tell you that he was inspired by the “Seven Famous Weapons of Benkei[2] . The designation as the “Seven Basic Tools of Quality” arose in postwarJapan.
These diagrams are tools that organize a group or persons knowledge about the causes of a problem or issue and display the information graphically.
It was originally created and used by Dr. Kaoru Ishikawa and is sometimes called an Ishikawa Diagram. Also, because of its shape it is called a Fishbone Diagram. In general what you do is brainstorm ideas (causes) then group them in to categories. Those categories become the many branches of the Cause and Effect diagram.
This is another simple but powerful tool. Check Sheets are lists of items and the frequency that the item occurs. They can be made in so many different ways that many times, we don’t think of them as a list, but they are. below are two, one that kind of looks like a list the other not so much. On the shoe the defects are marked with an “x” in the location it was found.
They are use to answer many important questions such as:
They are often used to remind individuals doing complex tasks of what to do and in what order. They are also used many times in conjunction with other tools to help quantify or validate information.
Control charts are the most difficult of the seven tools to use. They are seldom the method of choice. When a process step is important, we would prefer that the step not vary at all. ONLY when this can not be accomplished in an economical way does one choose to use a control chart. Below is an “XBar-R Chart” also called an “Average and Range Control Chart”.
Control charts are only useful if the step (operation or function), over time, exhibits measurable random variation. Control charts display the data over time (Time is on the x axis above listed as sample). Control Limits (the red lines) are displayed on control charts, where data falling within the control limits are considered “normal” variation. Any point outside the control limits are considered “special caused” variation and need to be look at and corrected through an action plan. If you create a control chart, you must also have with it an action plan.
Besides control limits for control charts, there are several other type of trends (runs) that can indicate an out-of-control process.
What I have shown above is only one type a control chart and one of the simplest to use but there are several others (not so simple to use). Below is a Decision Tree Diagram of the different type and there use. Be sure you understand the application of each control chart or get help if you plan to use one of these.
Histograms are a “picture” of a set of data (or information). It is created by grouping the data you collect in to “Cells” or “Bins” (Bars in the chart below).
Histograms take your data and give it a shape (Distribution). With this, you can see the data sets spread, central tendencies, and if it meets requirements. As you can see, it is a valuable troubleshooting tool. You can take it a compare differences between machines, people, suppliers etc. Never use a histogram alone always also plot it in a time ordered plot (run chart).
Pareto Charts are a specialized Histogram of count data. It arranges the Bins or Cells in largest to smallest counts and gives you an accumulation line as seen below.
The Pareto Chart gets its name from the use of the Pareto Principle which states “ 80% of the effect comes from 20% of the causes”. Vilfredo Pareto, an Italian economist, originated this principle by determining that 80% of the land inItalyis owned by 20% of the population. Later it was found to hold true in many things and help us focus on the critical few. With a chart like this a team can decide where to place its priority and focus ( the big hitters). This is extremely helpful when time and money is limited as it is in most cases.
Scatter plot are a very simple tool to use to see if there is a correlation between two things (i.e. does one thing lead to another). I always before going into any major analysis of data, plot the data in some way to get a “gut feel” of what is happening. This tool lets you create a simple picture showing how two or more variables change “together”.
As one can see in the chart above the fruit on the tree increase in weight the longer it is on the tree. In scatter charts we see if one thing relates (correlates) with another. Below is a set of chart that shows some of the relationships you might find with this tool.
To me Stratification is a catch-all for summarizing, picturing, or applying some tool to data so you can understand what is happening. Stratification is the process of dividing members of a population into homogeneous subgroups before using it. The data (strata) should be mutually exclusive: every element in the population must be assigned to only one subgroup (stratum). The data should also be collectively exhaustive: no population element (data) can be excluded.
That’s a mouthful, but if you look at above six tools all of them do this stratification of the data. In many texts they list either flow charts or run charts under this seventh tool area. A run chart is just the “Individuals Chart” of the above control chart without control limits. A flow chart takes a group of steps in a process and summaries them into a map of the way the process works. They are sometimes called a Process Map or a Process Flow Map.
They are created to:
Well there you have a short description of the Seven Basic Quality Tools. Stay in touch as I go into each tool with details of how to construct and interpret them. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
[1] Montgomery, Douglas (2005). Introduction to Statistical Quality Control. Hoboken, New Jersey: John Wiley & Sons, Inc.. pp. 148. ISBN 9780471656319. OCLC 56729567.
[2] Ishikawa, Kaoru (1990), Introduction to Quality Control (1 ed.), Tokyo: 3A Corp, p. 98, ISBN 9784906224616, OCLC 23372992
In Six Sigma, we are very focused on the Voice of the Customer and creating Value for the customer. But getting our arms around this thing value is not real easy. In fact, I believe that it is this constant changing of what is of value that keeps all Quality folks employed. You see, over time, customers change and what they think is of value changes as well.
Thirty years ago, if you wanted to send someone a message most of the time you would mail them a letter. If it was really important, you could fax or telegram them. But today we have Email, Twitter, and Face book. I am not sure anyone really writes letter today. So here, you see a change in what is of value to “customer” (at least customers of the post office). In today’s market, the Post office continues to raise rates to cover costs. There is a think called the Kano Model that explains this very well.
The Kano model is a chart with that has two axis and three levels of quality or characteristics.
The two axis are Customer Satisfaction (this is their perception of satisfaction) and Customer Expectation (this is the reality of how well the expectation was met [usually in a percentage]). Some have labeled Customer Satisfaction as Quality.
Customer Satisfaction – This axis runs vertical with the top end of the axis (scale) being extremely satisfied and the bottom of the axis being extremely dissatisfied.
Customer Expectation – This axis runs horizontal with the left end of the axis (scale) being 0% expectations met and the right end of the axis being 100% of the expectations being met.
Note: the two axis cross dead center of each line.
The three levels of quality or characteristics are Must (Basic Quality), Wants (Expected Quality) and WOW (Exciting Quality)
Must (Basic Quality; Dissatisfiers) – These are characteristics do not sale a product but the customer assumes they are there. These are things like brakes, windows and tires on a car. Customers expect them to be there and will walk if they are not. But they are not on the list of things (specifications) customer walk in looking for in a product. You will note that in the Kano Model (fig. 1 below) the MUST curve lies totally below the Customer Expectation axis line representing dissatisfaction. This means providing must characteristics alone will not satisfy the customer.
Wants (Expected Quality; Satisfiers) – These characteristics are what the customer wants to see. Here the customer has come in specifically looking for these. With items that are more complex the customer has a list, specification, or drawing that includes all of these characteristics. Examples of these are a particular color, and multi-year warranty, or a short wait time. Customer usually will use these to decide to buy or not. In the Kano Model, these characteristics (Wants) are a straight line. Where it shows the customer is dissatisfied if there Wants are not met. But their satisfaction increases as more of these characteristics are met.
WOW (Exciting Quality; Delighters) – These characteristics are sale the product if all the others are met. These are characteristics that are above and beyond the customers expectations. Here the customer receives more than they expected. Examples of these characteristics are: collision avoidance systems, life time warranties, and free upgrades for life. In the Kano Model, the curve for the WOW characteristics is completed above the customer expectation axis.
Figure 1: Kano Model
You will notice another line in this model in the upper right hand corner labeled “Competitive Push”. This is what represents the “ever changing customer voice”. You see things that WOW, delight and are unexpected today will be wanted and expected tomorrow (in the near future) and become must have and basic requirements further into the future. Things never stand still. Having a Desktop Computer instead of a mainframe terminal was a WOW in the eighties. In the nineties Desktops were wanted/expected and the Laptop was a WOW. Now Desktops are Musts with Laptops a Want and the IPAD the WOW. Who no’s what is next, but I can bet someone is coming up with that next WOW that will push the Desktop off the chart just like the wire dialup phone and the pay phone booth.
This model gives us an idea of how customer’s expectation (value) is constantly changing. One they see something they like most likely someone will make it affordable for that customer and soon. Who know some day we will all have a spacecraft in our garages and there will no longer be a need for streets. What a confusing airspace we will have. Oh well expectations will keep changing and those in the quality profession will constantly be watching for those shifts in customer expectations.
Well there you have my thoughts on the ever changing voice of the customer and the Kano Model. I hope this helps you with your projects' focus on customer value and where it might have moved.
Oh, think what would happen if where you worked moved its product focus to a different industry, group or customer set. What happens to the model now?? Most likely, all the characteristics would still exist, but the customers expectation of each may change dramatically. Wow’s, What’s and Must’s could be totally reshuffled.
If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
As practitioners of Six Sigma you may have caught this, but there are two important elements that the NFL talks have missed and I feel will lead to poor results or none at all. These two important elements are the concept of Customer Value, or some may say “stakeholder” value. Second is the concept of Teamwork. This second one I would think they would get since Football is a “Team” sport, but maybe not.
Customer or stakeholder value in solving an issue, involves insuring we know who the customer and or stakeholders are. Generally speaking you look at where the money comes from, Customers (fans). This is why in most places we talk about “customer Value”. I also like to expand the “customer” to be all stakeholders because without all stakeholders a product can not be produced. So I define Stakeholders in three. Those three groups are:
1. Customers – Where the income (money) comes from.
2. Stockholders/owners – Who’s money is invested in the business and that investment is being spent to produce the value for the customer. Yon this group because in all businesses you have to spend money to make money. Customer pay for product at delivery usually not in advance.
3. Employees/ Players – Who perform the “manufacturing of the product” for the customer.
Both the Stockholders/owners and the Employees/Players are investing time and/or money to create a value for the customer.
So where is the customer in the NFL talks? In businesses that are working similar issue this point and input would not be left out of the discussion, where clearly it is in the NFL talks. Businesses include them because the solution may not even be focus on increasing value to the customer. Which means insuring that the change will increase customer value thus increase profits. When customers are left out ( even though they don’t know they are) they go some where else. That is what happened in the steel industry. That is also what was and may still be going on in the automotive industry.
By the way value can be defined (Seen) by asking three simple questions and you are creating value IF and only IF you answer yes to all three. They are:
Teamwork in not decision making by concession or compromise it is decision making by consensus or accord. To do that you have to pick you team members carefully. They need to come from all three stakeholder groups and each member needs to have the following qualities:
As you can see not all the stakeholders are on the team and those that are there do not or will not agree with the 6 items above. In the six sigma world of problem solving this will only lead to disaster.
Well there you have my thoughts on the NFL talks. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
In Six Sigma we use a five step process (DMAIC) based on facts and data focused on our customer value to grow the business. The idea is to improve the process; make things better; make step function improvements. But as I say that I have seen perfectly run projects get to the end of analyze and are killed when they start to make the improvements. Killed by management. What has happened? To understand that let’s look at the objectives of the Analyze step and the Improve step.
Analyze: Analyze the current state data and determine the Root Causes (opportunities to improve).
Improve: Develop and implement the best plan for improvement of the opportunities (Root Causes) identified in the Analyze Step.
The problem I have found is that teams focus is on one root cause and what they perceive as the best solution to that root cause. That does meet the objectives but the team is made up of experts and others involved in the process at hand. They do not see the bigger picture from the total company or corporation view point. What usually kills the project is the solution is not acceptable to upper management and it is upper management that are the experts of the top level company/ corporate view of things. The L1 (level 1) Map of an organization. The team is usually working (and are the experts) at a L3 or 4 of the company. So how do you solve this problem. By doing two things.
1.) Make sure that your top level management sponsor is constantly up-to-date on all the teams activities. That they are PART of the team where they will see these problems coming. They are part of that management expertise that can see issues that will cause a solution, that looks obvious, to not work for the company as a whole. This is one reason why in Define you want a top level manager that has “scheduled” their time to work with the team. They have to be committed not just supportive of the team.
2.) Every problem I have seen has had more that on Root Cause. Each root cause also has more than one solution. Make sure you have multiple ways (options) to solve your problem. Yes, one of the causes will be the biggest and to solve it there will be one way that gives you the best return on investment, but you need to propose several ways to solve the problem, some better than others but all make an improvement.
Now when you pitch your solution to management you give them several options that your top level manager/sponsor has seen and supports. Management can look at what you propose and select the best way from their expert view point. Yes, I would push the teams solution but management should be able to tell you why they would not go with that one and as such your can propose a alternative that you have already developed that avoids the issue they see.
When a team does this they never seem to fail at this point in the project and they tend to go on to success.
Well there you have my thoughts on picking the right solution. It more like picking the right solutions. I hope this help you with your project and brings you to success. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
In reality this is only non-numeric in the sense that it is data we collect about the presence or absence (nominal data) of some characteristic or attribute of an item. Usually we take this data and transform it into a count of the characteristic; like the number of “naughty” or “nice” kids on Santa’s list. Or, more practical to some, the number of red cars going through an intersection; the number of order forms with mistakes in them, etc. These counts are all called nominal scale measurements. This scale of measurement gives us the least amount of information of the four types of measurement scales (Nominal, Ordinal, Interval, Ratio).
The question I’d like to address here is once you have the data how can you compare it to a standard or another collection to determine if there is a significant difference between the two. An example of this is with order forms. Say you made, what you think is an improvement in the way you handle orders but you really want to know if there actually is an improvement. How do you do that? You can use what is called the Chi Square Test.
Chi Square Test is used to evaluate count data presented in 2-dimensional tables (rows and columns) to answers the question: “Do the groups differ with regard to the proportion of items in the categories?” In our order form example we might have these three categories: No Errors, Minor Errors, and Major Errors. We would collect data from these three categories, before and after the improvement.
Lets say before the improvement we had 60% error free, 30% minor errors and 10% major errors. After the improvement we looked at 136 orders and found that 93 were error free, 33 had minor errors, and 36 had major errors.
Our two dimensional table would look like this ( In this table Chi Squared is the value marked X2):
For those who want to calculate the Chi Square value the formula is below:
BUT !!! there is an easier way using Excel formulas. To do this we need to use the “CHITEST”formula in Excel.
So in our example I entered the formula: =CHITEST(Actual Range [new process], Expected Range[old process]) OR =CHITEST(B2:B4,D2:D4)
As you can see this gives us a formula result of 0.0000004152 or 0% [.00004152%]. This says the probability that the new and the old process are the same is 0%. The two processes are different! Looking at the counts you can see the new process improved minor errors but increased major errors. Go back to old process!
Well there you have my thoughts on comparing non-numeric data. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
Ordinal data is information that you collect on items that you can rank order some characteristic or attribute. Examples of this type of data scale is the count of food items on a table that taste excellent, good or bad. Another would the count of dress that are very attractive, look OK, or are ugly. You can see with this type of count data you can arrange the counts in order of best to worse. This scale of data gives us more information than Nominal scale but not as much as the other types of measurement scales (Interval, Ratio). Scales are ways we collect data.
So once we have done this data collection how can we look at the data to see better what we found? Well for this scale there two types of correlation tools one can use are Pearson correlation, Chi Square which are some what complicated. But one of the simplest is Spearman’s Rank order correlation. In this correlation you are comparing how two people/inspectors/groups correlate with each other. This will let us know if the two saw things the same way or not. This could be anything like rating several wine, movies, cars, TV’s etc. For example if you had two friend (x and y) rate 5 movies (A, B, C, D, E) from best(1) to worst(5). you would create the below table and chart to compare your friend results and tell if they look at these movies the same.
Well there you have my thoughts on tools to measure the Ordinal Scale. Next time I am going to discuss the different statistical tool used for the Interval scales of measurement. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
Just to refresh your mind Nominal Data (Count Data) is information that you collect about the presence or absence of an attribute (characteristic). Like the number of “naughty” or “nice” kids on Santa’s List. Or, more practical to some, the number of red cars going through an intersection; the number of Order forms with mistakes in them. These counts are all, what we call, nominal scale measurements. This scale of measurement gives us the least amount of information of the four types of measurement scales (Nominal, Ordinal, Interval, Ratio). Scales are ways we collect data. For instance here we are counting the occurrence of something which is what is called a nominal scale.
So once we have done this counting how can we look at the data to see better what we found. Well for this scale there are a few good tools.
Percentage (%) – This gives you a feel for of all the things you saw, how many were what you were looking for. For example lets say you sat at an intersection and counted red cars going through that intersection in one hour. And during that hour you saw 300 cars go through that intersection and 30 were Red. That would mean that for that hour 10% of the cars that went through it were red. (30 red cars/300 cars through the intersection*100=10%).
Proportion (1/10, 1 in 10) – This, like percentage, gives you a feel for of all the things you saw, how many were what you were looking for. This gives you one other piece of information and that is out of how many you looked at. This, if you are doing the study for yourself, may not be important, but if you are convincing others with a percentage they may want to know how many in the total count. A good example where I like this best is on the internet when looking at customer ratings (those stars showing you that customers really liked the product. I always want to know how many customers actually rated the product at all. When you see 1 to 5 I am not impressed. But if there was 100 now I feel better about the rating. Remember that 100% liked something out of 1 (1/1) customer is different that 100 (100/100).
Chi-square Test (X2) – There are many times where we want to compare the percentages of items in several different categories. For instance, instead of just red cars we want to collect the number of all cars by color (not just red). It might be, instead of cars, operators, materials, TV channels, Hospitals or any other grouping we might have in mind. In any of these groups your could collect data and place it into different categories (Colors, Sizes, Ratings). The results can be put into what is called a Chi Square Table to answer the question ”Do the groups differ with regard to the proportion of items in the categories?” An example that one could use Chi-square test would be: (The following example is from Narrella(1963) and the Six Sigma Handbook [Pyzdek, 2003]).
Rejects of metal castings were classified by cause of rejection for three different weeks. The question that the Chi-squared test would help answer is: “Does the distribution of rejects differ from week to week?
Well there you have my thoughts on tools to measure the Nominal Scale. Next time I am going to discuss the different statistical tool used for the ordinal scales of measurement. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
[Note: Most of the information for this article comes from “The Six Sigma Handbook”[i]]
Why do we measure things? To see how things are, or if change has occurred or to understand something. Measurement is just looking at something and describing it in numbers. The rules (mapping functions) that we use to describe the “thing” in numbers provide us with a model of reality. If this model is correct (valid) we can learn about the real world by studying the model and the numbers that it predicts. Without these measurements systems astronomers could not describe the make up of galaxies billions of light-years away from us.
Every questions we have starts in the real world But to understand the question and come up with the answer we use mapping functions (rules) to describe the real world question using numbers. There are times when we map to a non numeric entities in the real world, Like a question about color but we convert these into numbers like the number of red things in a room. These characteristics (elements) are X’s. The “numbers” are Y’s derived using the mapping function as a transfer function of the elements into numbers.
A good example of this we all can relate to is the fuel tank on your car. It would be nice to know how much fuel is in your tank? That would be a measurement of the amount of fuel in your tank.
Real World - Your fuel tank with some amount of fuel in it.
Mapping function – A float with a sensor on a spindle connected to a fuel gage. The gage marked off in numerical intervals. Plus YOU reading the indicator.
Numbers – The gage needle pointing to a numerical value on the gage (like the 1/8 mark just above Empty (0))
Usage – Time to get gas!
Not all data (numbers we collect) are created equal. That does not mean some are better than others is just means that some tells us more information than other. You will find that our numbers fall into one of four scales. In teams that I have worked with I always bring up the discussion of measurement scales because not everyone looks at how they would measure something in the same way. Some may look at the fuel tank about as fuel empty or half full, other may talk in gallons of fuel. With that said we need to understand the scale we are going to measure the real world in. The scale of the data to be collected in the measurement process. .So here are the four measurement scales.
Well there you have my thoughts on Measurement and the importance of your scale of measurement. Next time I am going to discuss the different statistical tool use for different scales of measurement. If, you have questions or comments please feel free to contact me by leaving a comment below, emailing me, calling me, or leaving a comment on my website.
Bersbach Consulting
Peter Bersbach
Six Sigma Master Black Belt
http://sixsigmatrainingconsulting.com
peter@bersbach.com
1.520.829.0090
[i] Thomas Pyzdek The Six Sigma Handbook, 2003, McGraw Hill
1/26/12 – Lean Six Sigma Black Belt Training Comment
Friday, January 27th, 2012I liked the format of this on-line course. The video ”"lectures”" were great. Concise yet thorough. The assignments made a big difference. If I had not done the assignments, I would have left with an incomplete understanding of the subject matter. The fact that Peter also held me to a high standard was important. The mini lectures on various topics using Minitab and Excel, for example, were also very helpful. They saved me a lot time yet pointed me to the right location in the application. I did get stumped on the modules dealing with distributions. It took a couple of weeks (!) to feel comfortable with that subject.
Tags: Customer Value, lean Six Sigma Training, Six Sigma Process, Six Sigma Success, Six Sigma Training
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