The purpose of the Six Sigma Process is to identify and contain the vital few variables that are impacting an output variable in a negative way.
When this is done:
Six Sigma, Lean Six Sigma, and Design For Six Sigma PowerPoint Training Slides
The objective of most businesses is to maximize profit and grow. This is largely achieved by satisfying customers, and to the extent that we satisfy customers we ensure future survival and prosperity.
The Six Sigma process uses the expression Y=f(X). The goal of all Six Sigma projects is to solve this equation. In practical terms it's stated "Y is a function of X". It means that the "output (Y)" is a function of the "inputs (X)". It reflects the fact that a causal relationship exists in all process actions that we perform.
In reality, a result is seldom defined by a single input (X), so we extend the concept to say "Y is a function of one or many X's" where Y is the dependent variable and the X's are the independent variables.
Dependent And Independent Variable Examples
Customer satisfaction (Y) is a function of quality (X), delivery time (X) and cost (X) of the product and/or service that we provide. The term “Critical-to-Satisfaction” refers to any variable(s) that has significant influence on any of the three determinants of customer satisfaction.
Six Sigma utilizes specific tools, in a specific order, to solve business problems.
Six Sigma process tools are used to:
Kicking-off a Six Sigma project you're faced with all possible causes - the “vital few” mixed in with the “trivial many".
Using various Six Sigma tools and techniques, data is transformed into the useful knowledge needed to find the solution to the problem.
Six Sigma itself has not created new tools. It has packaged existing quality improvement tools and it's the appropriate application of the tools that makes all the difference.
Additionally, the use of the tools is additive; that is, information garnered from one leads to the use of another until such time as the sought after answers are obtained.
As you go through the application of the Six Sigma DMAIC process, your goal is to find the root causes to the problem you are trying to solve.
To aid you in doing this, Six Sigma tools are used that take in a large number of the “trivial many contributors” and narrows them to the “vital few contributors”.
Six Sigma tools are used to sift through the many inputs to define the key inputs driving the process.
What’s The Big Picture (Y)?
You need to have a reason to enter the Six Sigma process and that reason must be that something is bothering a customer, either internal or external.
What’s critical-to-satisfaction, $$$$, cycle-time, defects, etc.?
Critical-To-Tree Example (Quality, Delivery, Cost)
What‘s The Specification?
If you don’t know what makes something good or bad how can you measure it? The definition of what makes a "defect" must be crystal clear in the Six Sigma process and in the same units-of-measure as the CTS from step 1. If it's not you have the wrong specification.
Can I See?
If you can’t measure something, how do you know where you are, where you have been, or where you are going? If your measuring system is incapable STOP and FIX IT before the project goes further.
Actual Value + Measurement System Error = Observed Measurement
space block
Variable and Attribute MSA Approaches
What's The Current Performance?
I know what needs to be fixed (step1), what defines it as good or bad (step 2), and that I can accurately measure it (step 3). Now we can say how the process is performing. Real improvement can happen from here!
Process Capability Study Key Statistics
How Much Improvement Can We Make?
Where do you want to be at the end? Is it aligned with the business strategy? The Six Sigma process must be aligned with company strategy.
Cycle-Time Quality Improvement Objective
What Makes It Tick?
List all potential inputs (X’s) that could be impacting the output (Y’s). This is filling the top of the funnel.
Think outside the box and identify all possible causes. If you fix it the same way you did last time, you will have the same problem you have now. The Six Sigma process is about permanent fixes.
Identifying The "Viatal Few" Input Variables - Process Map, Fishbone and Pareto Results Feeding Into C&E Matrix
Assessing Risk - Process Map and Pareto Results Feeding Into Failure Modes & Effects Analysis (FMEA) Tool
Assessing Risk - Process Map and Pareto Results Feeding Into Failure Modes & Effects Analysis (FMEA) Tool
Process Map, Capability, MSA and FMEA Results Feeding Into The Development Of A Control Plan
Discover Input (X's) Output (Y) Relationships
This is getting to the middle of the funnel. Screen using graphical tools, experiments, and hypothesis tests to identify and prove which are the vital inputs (X’s).
Discover input ( X’s) and output (Y) relationships. For simple projects you may get to the bottom of the funnel with 1 vital input (X).
Matrix Plot Results Exploring Relationships Between Variables
How Are The Inputs (X’s) Affecting The Output (Y)?
Evaluate how the vital inputs ( X’s) affect the output (Y), either independently or in combination. This is primarily done with regression and DOE. This is the bottom of the funnel.
I know which inputs (X’s) are impacting my output (Y). And now I know how they affect the output (Y).
The function Y = f(X1, X2,…, Xn) is called the “transfer function” – it describes how a change in one or more of the inputs (X’s) transfers to a change in the output (Y).
In practical terms it means “the output (Y) is a function of the inputs (X’s). "Y=f(x) is the Six Sigma process".
Exploring The Strength Of Relationship. Developing The Sigma Sigma Equation.
How Do I Set The Inputs (X's) To Maximize The Output (Y)?
We know which inputs (X’s) are important and how they impact the output. What settings of the inputs (X’s) do I use to make the improvement?
In the case of variable inputs (X’s), my settings must be a target value and tolerance (amount ± about the target). In the case of non-variable inputs (X’s), the best value of the input (X) variable that provides the best value of output variable (Y).
Can I See When My Critical Inputs Change?
Validate the measuring systems of the vital inputs (X’s).
Also, you might have improved your output (Y) so much that you can no longer “see” the process improvement. You may need to improve the measurement system to truly measure the improvement.
How Much Improvement Did I Make?
Measure the capability of controlling the inputs ( X’s) at their optimal settings. Conduct a process capability study on the output (Y). Determine results by comparing the new capability with the baseline capability (step 4) and your goals (step 5).
Let’s Not Repeat This Again!
Before you can say that a project is complete; the inputs (X’s) you determined as vital, their settings, and other actions you have taken to make the improvement must be:
space block
DistributionsDOE |
SPC |
Get a Free Six Sigma Tool & eBook Monthly
May 10, 16 09:24 PM
A Quality Control Plan is a documented description of the activities needed to control a process or product. The objective of a QCP is to minimize variation.
May 10, 16 08:49 PM
The Largest Collection of Free Six Sigma Tools and Training on the Web!
May 10, 16 07:28 PM
The Weibull distribution is applicable to make population predictions around a wide variety of patterns of variation.