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Chapter 21: D. Quality Tools and Techniques 319
The five steps of SS are most commonly referred to as the DMAIC methodology.
Upon further analysis, we can see that each of the outcomes of the scientific
method are found within the DMAIC methodology. Two primary points differentiate
the scientific method from SS: 1) use of quality-specific language and tools,
and 2) use of the DMAIC methodology occurs in quality-related problem solving
when certain financial constraints or expectations have been met. The financial
constraints or expectations are related to the amount of cost savings expected
as a result of problem-solving activities to justify use of the comprehensive and
systematic DMAIC methodology. It is beyond the scope of this book and the
Certified Quality Inspector Body of Knowledge to provide further content on SS
and the DMAIC methodology. It should be emphasized however, that SS and the
DMAIC methodology are, and will remain, a critically important problem-solving
approach within the quality community, and the CQI is strongly encouraged to
continue their professional development by learning more about this topic.
The goal of all approaches to problem solving is identifying the reason(s) why
a problem occurred. The process of identifying the true underlying reason(s) a
problem occurred is known as root cause analysis (RCA).
ROOT CAUSE ANALYSIS
RCA is an approach to problem solving based on the identification of the true
underlying reason(s) why a problem occurred. RCA is critically important
because any corrective action taken on a non–root cause issue or item will result
in the problem remaining active within a selected process. By remaining active,
we mean that misapplied corrective action on a non–root cause issue or item may
change the appearance or manifestation of the original problem, but the original
problem still exists.
As with the other problem-solving approaches discussed above (that is, the
scientific method and SS), RCA makes use of many of the quality-related tools
and techniques discussed thus far in this book. Also consistently with the other
problem-solving approaches, RCA is intended to be iteratively applied wherein
with each iteration we contribute to continuous improvement. Also consistent with
the other problem-solving approaches, RCA has a structured approach, which
includes the following:
• Define the problem(s)
• Identify manifestations of the problem(s)
• Collect data
• Identify root causes
• Propose solutions
• Test solutions
• Verify effectiveness of solutions
Part IV.D