The Analyze Phase
The Analyze phase is the third and usually the longest phase in the Six Sigma methodology. This phase has the most Six Sigma tools available for use. Most of the crucial data analysis is performed in this phase. This eventually leads you to isolate the root causes of your problem and provides insight into how to eliminate them.
Tasks performed in the this phase
When you enter the Analyze phase, you should already have precise and accurate measurement systems for your inputs and outputs. Now that you are confident you will get accurate measurements, it is time to start collecting data.
In this phase, you collect data on all your inputs and outputs and then use one or more of the statistical tools to analyze them. The first thing we are trying to find out from our analysis is if there is a statistically significant relationship between each of the inputs and the outputs.
The second objective of this phase is to find out how they are related. In statistical terms, we call this "modeling" the relationship. The modeling will help us understand things like, "How much will the waist size of the jeans in production increase or decrease if I increased the temperature of my wash by 1 degree Celsius?" In this case, the input or factor is the temperature of wash and the output is waist size. Tools such as regression can help you see the relationship and model it.
There are many tools that can help you analyze, relate, and model inputs and outputs. The type of tool that you end up using will depend mainly on the type of data that you have. Depending on the whether it is continuous or discrete data, the type of distribution it has, whether they have equal variances, etc will decide which tool or tools you will use to get to your conclusions.
By the end of the Analyze phase, you should have filtered or "funneled" down the inputs quite dramatically. When you start your project you will probably have over 20 possible inputs. By the end of the Measure phase, you would not have eliminated any inputs but you would have prioritized down to perhaps the 10 or 12 seemingly most important inputs. By the end of the Analyze phase, you will probably have only about 6 or 8 inputs left.
Now that you have the significant inputs and a good amount of knowledge about them in hand, it is time to move to the Improve phase and figure out what to do with them!
Some of the tools used in this phase…
Regression, Correlation, Analysis of Variance, Hypothesis testing, t-Tests, Chi-Squared Tests, Graphical Analyses, GLM, Logistic Regression
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