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How to measure and chart in six sigma: Featured Article
Measurement is one of the most important parts of Six Sigma implementation.It is essential to have a uniform reporting and collection processes throughout the implementation so that the decisions made are actually based on accurate information.
In other words, the purpose for measuring and charting in Six Sigma is to create a way to quantify cost, speed and quality and to use charting to create a detailed map of the process, data on key input and output variables, and an analysis of the capability of the process. The six sigma tools for measuring and charting include the following:
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- Prioritization Matrix
- - Process Cycle Efficiency
- - Time Value Analysis
- - Pareto charts
- - Control charts
- - Run Charts
- - Failure Modes and Effect Analysis (FMEA)
Measurement is the "M" in the DMAIC methodology for six sigma implementation.Many agree that the measurement aspect of this approach is what makes the six sigma method a success even when other attempts at making a change have failed.In the measurement phase of the implementation process it is the responsibility of the team evaluating the measurement system to observe the process, gather data and then chart that process.
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Six Sigma Tools for measuring and charting
Here you will be able to read a brief summary of the most important tools that those implementing the six sigma process use to drive quality improvements within the DMAIC model.For larger companies with the resources to buy computer software programs tailored to their needs, these tools for measurement and charting are all done with a click of the mouse.Note that these tools are generally categorized into either a group of process optimization tools or statistical optimization tools.Process optimization tools enable teams to design more efficient workflows while statistical analysis tools enable teams to analyze data more effectively.Here are the descriptions of these tools:
Helpful Resources: 1. Statistical Definitions Before you can start to measure and chart in six sigma, you must first understand what the various tools of measurement and charting are.The dictionary that you will find through this link can help remind you of these statistical definitions. 2. Different Measurement and Charting Processb 3. Continuous Process Improvement 5. Six Sigma Implementation 7. Measuring and Charting Processes of Six Sigma 9. Control Chart Explainations 10. Professional Assistance |
Quality Function Deployment, otherwise known as QFD is used to help understand what customers are really looking for and what they require out of a product or service.The deployment aspect is present because quality engineers used to be sent on location to fully understand a customer's needs and expectations.The physical movement may not actually happen today but the term deployment has stuck anyway.The needs of customers are rated on a numerical scale with higher numbers equated with higher importance and lower number values to lower importance.Different design options are them developed depending on what the customers have said is most important to them.The expectation is that they product or service will be more effective at addressing the concerns of the customers more fully than ever before.Each option is listed and evaluated on how well it addresses the customers concerns.Each option earns a score based on how well they are able to fulfill these demands and then the best choice is determined based on the scores.
Fishbone diagrams are also used in Six Sigma as a charting of outcomes.This is used specifically when the results of one approach is measured independently from others.This is a cause and effect diagram that can be used in a fishbone diagram or cause and effect matrix to show the results of efforts taken.The fishbone helps to clearly identify the variables that should be studied further to reach the greatest benefit.The fishbone diagram looks somewhat like a fish skeleton and this is where it gets its name.To make a chart of this type you begin with the problem you want to know more about and this becomes the head of the fish.Then you draw the spine and six bones branching off the spine where you can list possible variables that could be causing the problem.Each bone on the spine is for a category of input.When all the variables have been listed then a team analyzes the diagram and finds the most likely sources of the problem then committing to further analysis.
A Cause and Effect (C and E) Matrix, which was mentioned above is an extension of the fishbone diagram and the methods used to create it.It is used to help the people using Six Sigma to identify and explore all the possible causes of a specific problem and then to find the true root of the problem.
Failure Modes and Effects Analysis or FMEA is used to identify ways a new product or process might fail before the failure actually happens.It is more about the activities and projects of the company in general than the specific methods of Six Sigma.It is similar to QFD in its basic structure and the first step is also to identify all of the possible scenarios in which failure could perceivably happen.Then an action plan is drawn up to make sure that these potential problems don't actually make it into the production process.They solutions are ranked on how well they address the concern and are rated from best to worst.This them helps the team working on this project to determine what actions should be taken to avoid the problems and make sure they don't actually make it into production lines.
A T-test is a method that is commonly used in many different types of analysis and especially in Six Sigma.This is done to make a pros and cons, or similar comparison chart, about how you can change methods to improve them.A larger sample size is best for this type of charting but this may not always be possible.It helps to determine a confidence level in the decisions that have been made about possible solutions.This can be used as a follow up even after another charting method has already been used.
Control Chars are a statistical process that has become very useful in the implementation of Six Sigma.It basically uses statistics to measure and monitor the variation in processes.It is also known as Statistical Process Control or SPC.Control charts are used in Six Sigma to show the performance of a particular process on one axis against time on the other axis.This visual representation helps many people to understand more about what is happening in the production process and dramatic changes can often lead to a specific time or event that may have caused it or just shown the first time it was noticed.The main objective of control charts is to show variation in the processes of production so that any problems that are serious or often enough can be addressed before they continue or worsen.They can be used to find if the variation of a certain parameter lies within normal bounds or is outside of that range and needs to be corrected to ensure better quality.
Design of Experiments is used to optimize processes.When this happens all of the inputs involved are going to deliver the most stable and consistent output possible.The hardest part is sometimes determining what conditions will lead to the best results.Design of Experiments or DOE helps identify optimum input settings to give the best output as well.This can be very time consuming but can also lead to drastic changes in quality as well as quantity produced.The payoffs can be significant but there is also the value of understanding better the way the process works and how different parts affect others.
Statistical terms to know
When measuring it helps to brush up on your statistics skills and that means remembering what some of the most common statistical terms mean.Below is a list that you can review that will hopefully assist you in taking the measurements and creating the charts that will be needed.Additionally, knowing and understanding these terms makes it easier to interpret data and to relay or present that data to others.
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- Statistics- The study of statistics involves the collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions from that collected data.
- - Variable- A variable is a characteristic or attribute that can vary in its nature, taking on a variety of different values.
- - Random variable- A random variable is a variable whose values are determined randomly.
- - Population- The population is the group of individuals who all fit into the same group by means of sharing a common characteristic (usually a characteristic for which the purpose of the case is being studied).
- - Sample- A sample is a smaller group that is selected from the population.
- - Descriptive statistics- Descriptive statistics refer only to the collection, organization, summarization, and presentation of data.
- - Inferential statistics- Inferential statistics refer to generalizing hypotheses from samples to populations using probabilities.This is done through the performance of hypothesis testing, determining relationships between variables, and making predictions.
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- Qualitative variables- A variable that is not valued with a number.
- - Quantitative variables - Variables that can be counted and numbered.
Of course you need to keep in mind that these measures and charts are only useful when there is a primary goal in sight and mind that you are working towards.
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