You are here: SixSigmaCertificationCourse » Six Sigma

Different types of Matrix Diagrams

Matrix diagrams can be sorted into several types depending on the number of data sets being compared.

  • L-shaped Relates two sets of elements to one another or a single set of elements to itself.
  • T-shaped Relates three sets of elements where there is no relation between the two sets that are related to a common set.
  • Y-shaped Relates three sets of elements where one set is related to the other two sets in a circular manner.
  • C-shaped relates three sets of elements simultaneously.
  • X-shaped relates four sets of elements.
  • Roof-shaped relates one set of elements to itself.

Prioritization Matrix

In the previous topic, you created a tree diagram. Key issues identified must also be sorted in the order of their importance. A prioritization matrix helps determine the order for dealing with different issues or selecting solutions according to their relative importance. In this topic, you will create a prioritization matrix to identify crucial issues that require immediate attention.

You must prioritize key issues identified according to their importance to determine which issues or solutions are the most critical and need to be addressed first. Using a prioritization matrix, you can determine such crucial areas where Six Sigma projects need be implemented to improve your business processes.

What are Prioritization Matrices?

A prioritization matrix is a tool used for determining the most important issues or solutions. This tool can be used for any prioritization activity. In a Six Sigma project, it can be used for filtering or prioritizing either causes or solutions. For example, the cause-and-effect matrix is a prioritization matrix used for prioritizing causes, while the criteria-based matrix is used for prioritizing solutions.

Whatever the matrix, the procedure used for prioritization is the same. The Six Sigma team identifies different criteria to be used for measuring different solutions. The relative importance of each criterion is determined and a numerical value indicating the weight of each criterion is entered in a column. Ratings are then assigned to the solutions against different criteria. The different solutions are scored against the identified criteria. Each rating is then multiplied by the criteria weights to obtain the weighted scores. The weighted scores are then added to find the cumulative value. The option with the highest total value is regarded as the option with the highest priority.

Prioritization Matrix

Fig: A sample prioritization matrix

What are the use of Prioritization Matrices?

  • Prioritizing complex issues involving several criteria against which the issues are assessed.
  • Assigning scores to the criteria or issues when data is available.
  • Choosing key areas to be focused upon immediately.
  • And, garnering team support and approval of crucial issues.

How to Create a Prioritization Matrix?

To create a prioritization matrix for determining key areas where Six Sigma projects need be implemented first:

  1. Gather the team members required to participate in the exercise.
    1. It is not necessary to limit the team to only the project team members.
    2. Involve all stakeholders who would have influence on the items to be prioritized.
    3. Ideally, the size of the team should be around eight.
    4. Agree upon the scope and the duration of the exercise because there is a tendency to drift from the main subject of interest, which may consume more time.
  2. Identify criteria against which the items to be prioritized can be weighed. Select the criteria according to your business and the nature of the process.
  3. Assign weights to the criteria on a scale of 1 to 10.
    1. Use an ascending scale while assigning the weight. Usually, the higher the better.
    2. Draw consensus within the team on the weights.
  4. Assign ratings for each item to be prioritized against different criteria on a scale of 1 to 10. Alternatively, the team can also pick solutions one by one and gather votes for each criterion. Members who agree that a solution fits a particular criterion vote for it. Ensure that necessary information is available to the team before voting.
  5. Compute the total score for each item.
    1. Multiply the rating for an item by the weight.
    2. Add the total scores for each item.
  6. Continue doing this for every criterion of all the items.
  7. Shortlist the items with higher scores for implementation.

Interrelationship Digraphs

An interrelationship digraph, also called a relations diagram or network diagram, is a tool that depicts relationships among different elements, areas, or processes through a network of boxes and arrows. It is usually used by Six Sigma teams to understand cause-and-effect relationships among different factors of a problem.

Different factors associated with a problem are entered in boxes or written on sticky notes. Factors related to one another are placed close to each other. If any factor causes or influences any other factors, then an arrow is drawn from that factor to those affected factors. At the end of the exercise, the arrows are counted. Generally, boxes with the most arrows leading to them are the major issues. However, this is not a hard-and-fast rule. Sometimes, even key issues may have only a few arrows. Therefore, no issue should be ignored. Issues that have more outgoing arrows are regarded as major causes, whereas issues that have more incoming arrows are regarded as major effects.

Interrelationship digraphs are used by organizations in different situations for varying purposes.

They are generally used for:

  • Analyzing any kind of relationship, besides cause-and-effect relationships.
  • Analyzing complex issues involving several interrelated issues.
  • Determining areas of improvement that will have the greatest impact on the
  • Analyzing logical relationships.
  • Analyzing problems where causes cannot be organized as hierarchies or matrices.
  • Analyzing a problem that is believed to be caused by another problem.
  • And, developing a better understanding of the relations identified using tools such as affinity diagrams.

Project metrics – Primary Metrics and Secondary Metrics

The metrics of a Six Sigma project reflect customer needs and ensure that the internal metrics of the organization are achieved. The selection of project metrics is one of the crucial elements in the Define phase of the Six Sigma methodology.

Six Sigma project metrics can be categorized into primary metrics and secondary metrics.

Primary Metrics

A primary metric, also called a project CTQ, is a CTQ measure that is used to monitor project progression and success. It is the reference point throughout the Six Sigma project. Ideally, project CTQs should have direct impact on customers. For any Six Sigma project, the primary metrics should be:

  • Tied to the problem statement and objective of the project.
  • In possession of an operational definition.
  • Measurable, simple, and expressed in the form of an equation.
  • Aligned to business objectives.
  • Tracked on hourly, daily, weekly, and monthly basis.
  • Expressed graphically over time with a run chart, time series, or control chart.
  • And, validated with a Measurement Systems Analysis (MSA).

Some of the primary metrics of a Six Sigma project include customer satisfaction, on-time delivery of products, final product quality, and less costly products.

Secondary Metrics

A secondary metric, also known as a consequential metric, is a project metric that you do not want to sacrifice at the expense of primary improvements in a process. These metrics ensure that the process is improving and not shifting one metric at the expense of another. It means that the secondary metrics have a relationship with the primary metrics of a Six Sigma project. Therefore, the primary goal of a Six Sigma project will be to move the primary metrics, but ensure that secondary metrics do not deteriorate or stay constant. Some of the secondary metrics include cycle time, volume shipped, inspection data, and rework hours. These metrics should not be sacrificed to achieve the primary metrics such as customer satisfaction, on-time delivery of products, and final product quality.

What are the sources of improvement projects?

Six Sigma projects are primarily focused on customers. The other areas that Six Sigma projects focus on are:

  • Improving the performance of Critical to Quality (CTQ)
  • Reducing the number of complaints from customers.
  • Reducing in-process or internal defects.
  • Reducing warranty claims.
  • Improving survey and customer research scores.
  • Capturing feedback from staff members effectively.
  • Increasing profits and revenue.
  • Improving audit scores.
  • Improving process performance and dashboard metrics.
  • And, having better growth than competitors.

Example of application of DMAIC methodology in IT sector

In the Define phase, the Six Sigma team in a software product development company found that customers identified many issues in the beta version of its software.

However, if all the issues raised were to be fixed, timelines would slip and the budget would increase. The team then calculated the number of changes and the time and budget required for fixing these issues in the Measure phase.

In the Analyze phase, the team determined if the changes were aligned with the scope of the project and then identified changes that should be made. It also identified conflicting changes pointed out by the reviewers, communication gaps between the developers and the customers, and ways in which changes were communicated to the developers as other major causes of the issues.

In the Improve phase, the Six Sigma team took several steps, such as determining the limitations of the software, having regular meetings with customers, identifying the appropriate application to communicate the changes to the developers, creating change requests, and monitoring the implementation of the approved changes until closure to eliminate the issues.

Finally, appropriate mechanisms were set up in the Control phase to monitor the regularity of meetings and communication between the developers and customers as well as to monitor the performance and usage of the change request feature.

Explain about the evolution of Six Sigma?

Six Sigma is a combination of the best elements of various quality improvement methodologies and a rigorous statistic-driven approach to performance improvement. The term “Six Sigma” was coined by Bill Smith, an engineer at Motorola. Six Sigma, in the present form, originated in the early 1980s at Motorola as a tool for reducing product-failure levels by 10 times in five years. General Electric (GE) implemented Six Sigma in 1995 after Motorola, and Allied Signal followed the Six Sigma trail after GE.

Six Sigma methodology evolved by combining the best elements of earlier quality improvement innovations.



Uniformity system
  • Introduced by Eli Whitney in 1798
  • Created a necessity for measuring dimensions
  • Evolved into specifications
Moving assembly line
  • Introduced by Henry Ford in 1913
  • Highlighted the importance of part consistency
  • Led to the sampling method, replacing 100% inspection
Control charts
  • Introduced by Walter Shewhart in 1924
  • Signaled the age of statistical quality control
Quality movement
  • Introduced by the Japanese in 1945
  • Pioneered the usage of data to quantify variation
  • Ensures integration of quality across all levels of an organization
Customer Centric Products
  • Japanese focused on eliminating defects and reducing cycle time
  •  Resulted in production of high-quality, efficient, and customer-centric products
.Zero defects
  • Was introduced by Philip Crosby in 1980
  • Led to perfection in a product, process, or service is attainable.
Quality standards
  • Introduced by the International Organization for Standardization (ISO) in 1987
  • Led to uniformity in quality practices across countries
Six Sigma
  • Motorola wins the first Malcolm Baldrige National Quality Award in 1987
  • Led to the present Six Sigma methodology

Need for Six Sigma and Goals of Six Sigma

The Six Sigma is an approach to business process improvement and performance management which encompasses a statistical and method-driven process. In order to effectively deploy the process in your organization, it is necessary to identify the basic elements that drive the Six Sigma methodology. Knowledge of the Six Sigma fundamentals is the first step toward a successful Six Sigma implementation. Before applying any business strategy in an organization, you must identify the goals and benefits of the strategy. You must also recognize the need for such a business strategy in the organization.

Surviving in a business world that is full of competition is crucial to any organization. Six Sigma provides the means to handle declining product prices in the market, which helps any organization compete with the best companies in business. It targets zero defects by setting a common performance goal for the entire organization. Six Sigma helps an organization achieve increased profitability and quality improvement rates, ahead of any of its competitors. Reduced scrap-related costs, rework, improved yield, and increased customer satisfaction are identified in companies striving to achieve Six Sigma.

A Six Sigma initiative differs from other quality improvement methodologies because it ensures that the costs involved in implementation are offset by the gains received from improvements. 

The primary goal of Six Sigma is to implement a measurement-based strategy in an organization that concentrates on process improvement and reducing variation. In addition to this, the other important goals of Six Sigma include:

  • Reducing the number of defects, leading to the improved quality of a product or service.
  • Achieving customer satisfaction by ensuring that customer expectations are met.
  • Reducing cycle time, which enables the faster delivery of products.
  • And, higher profitability by improving efficiency and effectiveness of the organization.

Sources of the Continuous Improvement or Lean Six Sigma Projects

In a Continuous improvement journey, improvement projects are nothing but the lifeline. In this series of articles, we covered on the Need for Project Selection and the Criteria for project. Now we’ll answer the big question – Where can I get my projects from? Essentially various sources of the project!

Customers Interactions: “Customers” are the biggest source for improvement projects. Classically, negative customer sentiments are good places to start. Your customers are unhappy, so it’s time to fix the issue. Mixed or ambiguous sentiments are also relevant places to start.

·Customer Complaints:If your organization has a list of customer complaints, then that is an apt place to commence. Complaints are not only sore for your customers, but for you too. Such complaints may cover a vast product or service attributes such as product or service quality, delivery time, responsiveness, people issues, pricing or areas of monetary impact including warranty claims,process & policy issues.

· Repeat Complaints: You can go one step further and target repeat complaints instead. Repetitive complaints from the same customer with the same tagging indicates high priority area for improvement.

·Enquiries & Requests: Few organizations target the need of customers to call or contact the organization and, reduce them. It might not be a complaint, instead just an enquiry or request. In other words, interactions with the organization that can be avoided. Looking at enquiries and requests serve as a proactive means to identify future problem areas.

·VoC Program output: If your organization conducts structured VoC surveys, then the outputs of such mechanism can be a good source of Continuous Improvement or Lean Six Sigma projects

·Customer Experience (CX) Dipstick: Customer Experience is usually hidden and not so obvious as customer feedback. Structured and unstructured mechanisms can be deployed to understand the customer experience. For example, many organizations now use mystery shopping to unearth issues in customer experience. Observation or Listening posts are also a good way to identify how customer experience can be improved.

First Time Right (FTR): If you closely have a look at your company’s process, you will find that there are many internal defects (work-in-progress) occurring, such as rework, repairs & in-process rejections. Such defects are silent killers because they drain organization’s efficiency and effectiveness silently. If your organization is measuring FTR, then its improvement can be an ideal project. More evolved organizations use RTY (Rolled Throughput Yield) as a metric which is also a good place to demonstrate Continuous Improvement.
However, most organizations have a simpler measure of success for quality – Defect Rate (% Defective). While there’s nothing wrong with this metric, is a bit holistic and hence factors leading to inefficiencies escape unnoticed with this metric. Nonetheless, it is good starting point for Continuous Improvement projects.

Reliability Data/Warranty data: Field failures are sometimes grave. It can cost you a lot and, the overall cost of ownership for customers might increase esp if the warranty is denied or the product is under breakdown. In broader terms, the principle of warranty is to institute accountability in the event of an untimely failure of an item or the inability of the item to perform its intended function. Experts consider reliability data analysis as a quality measure over time. This reliability analysis is done to analyze whether your product will survive for the time defined by the company in the normal conditions. Improving the reliability of a product can work both ways – organizations can lower its operational cost and provide longer warranty and customers would experience break down less often.

Process Performance Data: If your organization has a well-defined and structured reporting mechanism for process performance metrics, such as a dashboard or scorecard, then it would be a very good source to identify opportunities for continuous improvement projects. As leadership teams are consumers of such reports, such opportunities can easily gain sponsorship as well.

Competitive Benchmarking: Benchmarking is a continuous process of comparing your firm’s or company’s practice to those of the competitors or say most successful competitors. In certain cases, you might not be doing well. For example, having control over the delivery time to the customers. Then this can be taken as a project for improvement in our company. So, to generalize, competitive benchmarking results can also be a good source for Continuous Improvement projects.

Business Plans/Strategies: Gap between strategic plan and reality can be the cause of concern for leadership. Sometimes such problems may be because of supporting processes. They can hinder new business plans or strategies. Such process improvement opportunities are also a good source for projects, provided they are scoped well with well-defined objectives & goals.

Employee Feedback: While customers don’t see your process but only experience its outcomes, employees have an end to end visibility. They experience problems as customers and can associate inward aspects of such poor experience. Many organizations, pilot their products with employees, because employees are pseudo customers. If you can establish a structured process through which employees are encouraged to share their experience and enable them to take up such opportunities as Continuous Improvement or Lean Six Sigma projects, there’s nothing like it.

All the above can serve as a good source for Continuous Improvement or Lean Six Sigma projects.

Info graphic -Sources of the Continuous Improvement or Lean Six Sigma Projects

Criteria For Project Selection

We talked about the need for Lean Six Sigma project selection in detail in the earlier articles, in this one we’ll cover the criteria for selection and the in the following article, we’ll move on to talk about the tools used for selection and how to engage the stakeholders in the process.I have found that while leaders agree on the need for project selection, their views on the criteria is quite divergent. Most of them see this as a process to sway the process in favor of their priorities and interests.

There is nothing wrong in doing so, as long as the process is not biased.
Through this article, we draw consensus on the criteria and its relevance to the whole process.

The real good news is that the criteria for getting the project selection right are not too complicated.

What does project selection countdown look it? We’re going to start with the least of the top 5 criteria and find our way to the top most criteria.
Here you go:

7. Probability of Success:Not all the projects will be successful in any company. Hence, while selecting the project, most project leaders consider the contingencies which might come up and use that as a yardstick to select the project. Sponsors want their project leaders to be successful equally as projects leaders’ desire success. Well, sounds like a good approach. But doesn’t this approach make it very orthodox? Unlike other implementation projects in technology, improvement projects are bound to have ups and downs; and it is quite natural that not all projects achieve their goals. That is what continuous improvement is all about.

Thus choosing to play it safe isn’t the best criteria to select projects, though unfortunately, it is very popular criteria in use. That is why Probability of Success is the last in our countdown list! One of the organizations flips these criteria to select the project which has failed in the past or have a low probability of success as Black Belt project.  That is certainly a best practice to emulate.

6. Availability of Data:

Is data readily available for the project? If not, can it be easily gathered? While most project leaders and sponsors know that rarely will all the data needed for a project is waiting around to be analyzed. But they use the availability of data criteria to select projects because the unreasonable expenditure of time, resources and effort can be avoided. Yes, data is needed for analysis. But making it a criterion reduces the scope Continuous Improvement deployment.

Improvement projects are expected to venture into unchartered territories of the process and present root cause and opportunities. Getting people to measure something that is not being reported till now, in it is a feat. Having vanilla project can hardly be a criterion for project selection. That is why the availability of data comes second last in our countdown!

5. Savings potential:

Any project implemented, is implemented with an intention to gain any kind of tangible or say monetary benefits. But along with monetary benefits, there are other benefits like customer satisfaction, increased efficiency, total company involvement; increases workspace and much more. While it is absolutely apt to select projects which have savings to the organization, it is misleading to make saving potential a primal purpose of projects. I have seen many times, project leaders come up with simple ideas or improvements with a huge saving potential to the organization, but virtually no complexity involved. Such projects hardly qualify for Black Belt projects.

They best serve as Just Do It project. Giving undue importance to saving potential in project selection also sends the wrong message across the organization. That is why I not really excited about having this as a top item in the countdown. That’s why Saving Potential is only Number 5 in our countdown.

4. Apt Time:

There is always a perfect timing to initiate a project. Relevance is contextual. By apt timing, I mean both the time to commence, and the closure as per plan. An important project has to close on time. It has to be first of all, planned to close on time. It has to be scoped to close on time. That is why Apt Time is No.4 in our countdown.

3. Availability of Resources:

I don’t know if this has to do with the culture. Most organizations, if not all, end up with a laundry list of projects because everything seems to be Business or Customer priority. Even the biggest and richest of the organizations have limited resources. Either resource is depleted, busy elsewhere or simply not committed to deliver. The best person is often leading many projects, making everything he/she does venerable to failure. Project selection is about de-selection and not selected. Ruthlessly put ideas into a parking list for which right resources are not available; and if it is so important that it has to be executed now, then pull the right resource into this project rather than sharing.

While I have largely kept this point around manpower, it equally applies to money & time. I say with conviction that organizations that ensure that the leader of the Lean Six Sigma project is a dedicated resource, either full time or handling only one project even if it means he is part time on it are surely successful. This is why Availability of Resource is No.3 on our countdown!

2.Customer impact:

Ask yourself “will the results of the project bring any difference in the life of the customer? Will it improve the perception of the customers about the quality of your product or services?” Quite often this answer to this question is yes. Unfortunately, it’s motherhood in apple pie question. So insist on quantifying the impact.

If you can pin a number to the impact, then go ahead. And if you’re not able to do so, then there’s no point in wasting your time on the project. Consider Voice of the Customer in your organization as a starting point. Why don’t you start with complaints and alleviate customer pain? Thus Customer Impact is Number 2 in the countdown.

1.Business Priority:

Selection of projects is based on the need or priority of the business. Project leaders need to understand that the tail can’t wag the dog. Often, people package their ideas into a project and fuel it as an organizational priority. Scanning of the external and internal environment will give first-hand insight on what is the organizational priority, NOW? Go for it. Well, that may put you out of your comfort zone, competency or expertise, but remember that’s what the organization needs.

Without a real need, do you think any leader would offer sponsorship to your project or will it at all help anyone – NO.? That is why Business Priority is Number 1 in our countdown.

Project Selection and implementation of Lean Six Sigma is easy and at the same time should be handled delicately by keeping all the above aspects in mind otherwise it might turn into a big disaster. An effective diagnostic study is required before selecting projects and with the undivided involvement of the top management are pre-requisites for project selection.

Info graphic – Criteria for project selection

Criteria for project selection from Canopus Business Management Group