Six Sigma Analytics: Tools for Identifying the Cause of Product Defects

Six Sigma Analytics: Tools for Identifying the Cause of Product Defects

In every project that utilizes the DMAIC process, there is an Analyze phase where project teams are given a chance to identify production problems that may have led product defects. In this phase of the Six Sigma methodology, there are various tools and techniques that teams can utilize to determine the issues that occurred during production. These tools and techniques are designed to also help teams understand whether those particular issues caused the defects.

If you’re looking to better understand the reasons behind your product defects, this article will come in handy. Keep reading to learn more!

What’s the Analyze Stage All About?

DMAIC’s Analyze stage focuses on assessing and analyzing the data gathered during the Measure phase. This assessment’s main goal is to identify what caused defects in products. It is characteristic of Six Sigma to not leave the identification of problems and their causes to guesswork.

Below are the tools and techniques provided by Six Sigma to clearly identify the causes of product defects:

Cause and Effect Diagram

Also known as the Fishbone Diagram, this graphical diagram allows teams to identify the actual root of the problem, rather than merely its symptoms. This tool lets team members focus on the problem’s content instead of its history or the team’s individual interests.

In a cause and effect diagram, the problem is shown on the right side. Then, the team will work together to fill out the left side of the diagram, identifying possible incidents and occurrences that may have led to the failure or defect.

Process Map Analysis

With this tool, the team members identify the steps taken ever since the conception of the project until its completion. The entire process and steps are illustrated. All the data, tasks, variables, and decisions need to be completely identified and showcased. This tool makes it easier to see the exact stage at which the problem or inconsistency occurred.

Subprocess Mapping

DMAIC has a Define phase wherein the team draws a general map of the project’s entire process. A huge, complex process is usually made up of smaller processes, known as the subprocesses. In subprocess mapping, those smaller processed are identified and analyzed to see if any of them led to the defect or problem.

What Happens Next?

After using the tools above, the team should be able to identify a possible cause for product defects. The next thing to do is perform tests that will specifically determine if the identified possible cause is what really led to the issue. To do this, Six Sigma recommends utilizing the following techniques and tools:

Regression Analysis

This tool allows teams to estimate how the variables in a process impact each other as well as how those variables impact the final product. Regression Analysis also allows teams to measure the accuracy of theory in relation to data.


With this statistical testing technique, at least three groups of data are tested. It begins with a null hypothesis, where it is stated that the groups are similar and that there are no significant differences between them. Next, variation between and within the groups of data are tested. With ANOVA, a high variation between the groups of data is indicative that they are the root cause of the problem.


With this technique, teams can test whether there is a significant variation between the expected and observed results. A Chi-Square test also helps determine whether the variation can be attributed to mere chance or if there is an actual, independent cause.


Thanks to the dual nature of Six Sigma, teams can analyze processes and identify issues by using observational and subjective tools such as the Cause and Effect Diagram and Process Mapping. Then, teams can verify their theories using strict mathematical techniques such as Regression Analysis, ANOVA, and Chi-Squared tests.

Looking to learn more about the tools for identifying product defects?

At Leanoveering we offer the Six Sigma Yellow Belt program, the Six Sigma Green Belt program, the Six Sigma Black Belt program to help you with professional development. Get in touch with us today to see how Leanoveering can help.


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