Six Sigma is a fact-based, data driven philosophy of quality improvement used to drive business process improvement, customer satisfaction and bottom-line results.
The Six Sigma expert uses qualitative and quantitative techniques to drive process improvement. With the right tools, not only will there be an elimination of waste, but also an increase in profits and productivity of employees. Although the tools themselves are not unique, the way they are applied and integrated as part of a system is.
In this article, we present the top ten statistical and graphical tools commonly used in improvement projects.
Value-Stream MappingValue stream mapping
This tool, part of the lean six sigma methodology performs outlining of the materials and information needed to take the product to market, all the way to the customer. It is useful to streamline the process of production. While lean manufacturing is the predominant industry where value-stream mapping is used, it finds application across other several other industries as well.
The primary focus of this tool is to visualize the information as error rate, time period, and unnecessary delays that occur within the process. The value-stream map has three parts:
- Process Map: This contains all the steps included in the business process.
- Timeline: It comes from the process map for summarizing all the data that was used during the process.
- Information Flow: It explains the interaction that every step has with one another.
Cause-and-effect Analysis
One of the most common six sigma tools, cause and effect analysis allows for brainstorming the different causes of a problem. The cause-and-effect analysis diagram is also referred to as the fishbone diagram due to its resemblance to the fish’s skeleton.
Fishbone diagram aka Cause-and-effect diagramThe first step in this is to analyze and identify the problem for which the solution is being sought. Make sure that you note down where and when a process is occurring and who is working on it. In the next step, write down the issue on the left side in a box. Now, make a horizontal line that extends to the other side. From there, you will be making vertical lines that will be extending off giving a view like a spine. On each of these lines, you will be writing the major cause that can be behind this problem and the reason behind that cause. Next, you will be breaking down these causes into sub-causes. Once you are done with the diagram, you will have all the possible causes of your issue. You need to test and analyze this result.
The Five Whys
Sometimes, organizations may find an issue occurring repeatedly and no matter how many times it is fixed, it bounces back after some time. These problems are the result of a deeper underlying issue at the core. This is where a tool such as the Five Whys is useful.
The Five Whys methodCreated in the 1930s during the Japanese Industrial Revolution, this method involves asking the question ‘why’ five times. It is best suited in dealing with moderately difficult issues. Although it sounds like an unsophisticated method, when used in conjunction with other six sigma tools, the method yields impressive results.
Onedoes not necessarily need to ask ‘Why’ five times and may reach the root cause sometimes in one or two Whys itself. However, one may also end up going up to seven to eight Whys. In general, however, five Whys are observed. As a caveat, you are not to proceed further if you find the root cause going beyond your control. In these cases, you must take a step back and work on the root cause.
Kanban System
This is a supply chain control system focusing on cost reduction. This is done through the implementation of the inventory control system. Because of its potential benefits and ease of use, Kanban is one of the most famous six sigma tools.
Kanban methodLet us take the example of a supermarket. When the refrigerator at the supermarket is stocked, the store does not stock it up for months or years. Neither does the store keep products that it does not expect to sell right away. Similarly, in Kanban, you create a shopping list of products that you need, based on the customer's demand. Kanban uses this arrangement and makes the firm’s output controlled by its inventory supply.
The Kanban system is known for limiting the inventory-holding for all the business processes. This frees up additional resources which can be used better. There is a simple idea behind the Kanban system: activate the supply chain only when there is a demand for it. This brings focus to the business process and improves its efficiency.
Pareto Chart
This is a graphical representation of the Pareto Principle. It states that in any given situation, 20 percent of input will produce 80 percent of output. There are a line graph and a bar graph on the chart. The bar graph is representing the different metrics of the different components of the business processes. The line graph is representing the cumulative total of the metrics.
Example of a Pareto chartWith this tool, you will be able to visualize which part of the process will be influencing the output most. For creating such charts, the first step is figuring out all the processes’ components and measuring them. After you have completed this, you put the data into the Pareto chart. Every component has a big influence on the outcome. You will also be able to get an idea of what requires immediate attention.
Process Mapping
This is a method of visualizing the business process and having a better understanding of how it works. A map will be outlining the standard, roles, and responsibilities that are involved in the process. All the data is presented in a structured way displaying the steps of the process. This also includes what the inputs/outputs are, who is responsible for what, and what is the relevant information for the processes.
When it comes to process solving, business process mapping helps a lot. With this, you visualize the complete process which makes it easy to identify the issue, thus allowing you to get directly to the cause. Also, you will be visualizing the roles of the people that are involved in the process. With business process mapping, you will be able to find the potential risks created by the processes. While creating the map, you will have to rethink every step and look for any hidden liabilities.
Example of a high-level Process mapThere are several maps from which the most appropriate one can be chosen for your business processes:
- A flowchart is a less flexible process map. You can either draw it by your hand or use a software like MS Office. It is used for creating workflow diagrams.
- Swimlane diagram is just like generic flowcharts, only it has a better structure.
- The value stream map provides an in-depth option. It is hard to analyze it at first glance.
- Supplier Inputs Processes Outputs Customer (SIPOC) diagram is a simplified map focusing on the important aspects of the people and the process involved. It strips the extra information.
Project Charter
This is a document defining the scope and purpose of the project. You can use this as a blueprint of the business process and the project’s legal authorization. It contains the project’s scope and overview, details of the resources and the team, and its timeline. With this, you will have all the basic information regarding the project.
Project charterThe best thing about the project charter is that it keeps everything less chaotic. Once the team starts working on the project, it is easy to forget who is responsible for what, what deadlines need to be met first, etc. Things will get messier if the company doesn’t have a better managerial hierarchy.
With the project charter, you will be able to focus on what the project is all about. You will get a clear understanding of the structure of the project and what is the relationship among the people involved in it. It will help you bring order to your project and firm. This document is dynamic and undergoes evolution as and when project progresses.
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RACI Matrix
RACI Matrix or Responsibility Assignment Matrix is a table describing the responsibilities of every member of the team regarding all the tasks involved in the business process. The full form of RACI is Responsible, Accountable, Consulted, and Informed. Responsible is referring to who is going to achieve a specific task. Accountable is the one who assigns the tasks to everyone and monitors their progress. There is one accountable for every task. Consulted are a group of experts who will be providing their opinion to those who are working on the task. Informed are the people the team will be notified to after completing the task.
Example of a RACI matrixThe RACI matrix contains tasks and team members on the left side and the top row of the table respectively. The intersecting cells will contain a letter about what a person is handling in the task. This matrix helps all the team members to understand their role in the process. Also, it makes seeing the gaps in the structure of the team easy and what roles must be filled.
Regression Analysis
This is a statistical process used to eliminate and understand the relationship between the different variables. You can use it for defining the relationship between the input and the output variable. With this tool, one can visualize patterns or deviation from the patterns in the workflow.
Example of regression analysisRegression analysis is a reliable method of identifying which variables have impact on a topic of interest. The process of performing a regression allows you to confidently determine which factors matter most, which factors can be ignored, and how these factors influence each other.
While working on regression analysis, one needs to be cautious in avoiding statistical illusions.
Failure Modes and Effects Analysis (FMEA)
Failure Mode and Effects Analysis (FMEA) is a structured approach to discovering potential failures that may exist within the design of a product or process. Failure modes are the ways in which a process can fail.
The Failure Mode and Effects Analysis (FMEA) approachEffects are the ways that failures can lead to waste, defects, or harmful outcomes for the customer. The Failure mode and effects analysis is designed to identify, prioritize, and limit these failure modes.Lean Six Sigma practitioners often use this method to improve the quality of their services, processes, and products to detect and fix their problems even before they have occurred.
In conclusion, of the many tools available to green belts, black belts, and master black belts, these ten tools are the most common. While every project is different and may require a unique application for its own purposes, you will be hard pressed to find a project managed by a six sigma professional that does not use at least four of these ten effective six sigma tools.
