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How to Conduct a Simple Hypothesis Test in Six Sigma
I was teaching a Six Sigma Green Belt methods course in Washington, DC, and was asked to simplify the basic road map in Hypothesis TestingHypothesis testing definition A statistical hypothesis test ... Learn More..., so I thought; this is a great idea to publish as a blog post so that more people can have access to this valuable information.
In the example below, we are testing whether or not there is a correlationCorrelation is a statistical measure that describes the stre... Learn More... between two continuous variables.
Hypothesis Test Example
1. What is the practical question?
– Does an increase in tire pressure cause an increase in tread wear?
2. What is the X? (Input being Controlled)
– Tire Pressure
3. What is the Y? (What is being Measured)
– Tread Wear
4. Gather Data, Run the Analysis, and determine the Pearson CorrelationCorrelation is a statistical measure that describes the stre... Learn More... Co-efficient and P-Value
5. Run a Correlation Analysis (selecting the Pearson method). In this example the Pearson value ( r ) = 0.554 with a P-value = 0.0228
6. The results indicate that there is a medium correlation between the two factors and that the data set is significant at an Alpha riskAlpha risk (α) is the risk of incorrectly deciding to rejec... Learn More... levelStatistics level A statistics level is the value of input in... Learn More... of .0228.
A guideline of R Values:
- between -0.2 and +0.2 is the random chance of a relationship
- between -0.8 and -1.0 or +0.8 and +1.0 is a strong relationship
- the remaining levels/values indicate there is a weak to moderate relationship
Remember that correlation is not causation. It is only a test of the strength of the linear relationship of two continuous factors; so the R-Value indicates the strength of the relationship and the P-Value indicates the Alpha Level at the relationship can be stated to be significant.
We hope this simplifies the concept and serves as a guide to conducting a Hypothesis TestHypothesis testing definition A statistical hypothesis test ... Learn More... in a Six SigmaSix Sigma Definition: Six Sigma is a set of techniques and t... Learn More... method. What problems (or opportunities) would you apply this to in your organization?
Share your thoughts in the comments below!
