Hypothesis Testing in DMAIC Projects

Hypothesis Testing in DMAIC?
Jens Folke, Consultant, Denmark, Member
Sometimes a DMAIC project can be based on Six Sigma process mapping only, i.e. SIPOC/IPO/C&E/FMEA, and the process check is a revisit to the RPN of the FMEA. In other cases you may not have a sufficiently large sample size to conclude, e.g. 2 proportions sometimes require thousands of samples, so the answer is no: not mandatory.

Hypothesis Testing in DMAIC
Zafar Kamal, Consultant, Canada, Member
Dear Folke, thanks for your comment, I agree 100%. What happens if we eliminate hypothesis evaluation for any data?

Yes - Hypothesis Testing is Needed
James
If the solution is known, just implement it.
Otherwise DMAIC is a method to determine solutions when unknown. DMAIC uses various tools/techniques to sort out/drill down for potential causes. Then make a hypothesis ("Cause A impacts the result") and use facts/data to validate the cause before implementation. If you don't test your hypothesis the wrong potential solution may be implemented. HOW the hypothesis test is conducted may be a better question. But the idea behind hypothesis testing is valid for all DMAIC projects.

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