Analyze Phase of a Six Sigma DMAIC Project
The DMAIC is one of Six Sigma’s most effective methodologies for solving a problem. It consists of five steps, which are Define, Measure, Analyze, Improve, and Control. In this article, we’re going to talk about the Analyze phase – the third phase of DMAIC. Specifically, we’re going to talk about what this phase is and the tools teams can use to identify possible causes and perform root cause analysis (RCA).
What is the Analyze Phase?
As the name suggests, the phase involves analyzing the problem to determine the root cause. This allows the Six Sigma project team to tackle the problem at a deeper level and get rid of it permanently. In a manufacturing process, for example, this means investigating what is leading to defects in the products. This is something the customer does not want, which is also known as variation.
Tools for Identifying Possible Causes
The Analyze phase involves identifying all possible causes. Since this is Six Sigma, it means that teams are in luck. There are tools that they can use to take the guesswork out of coming up with potential causes.
Here are the most widely-used tools for doing this:
- Process map – This is a flowchart that shows the process in its current state. This means all the steps, actions, inputs, outputs, and other details are illustrated for a better understanding of the process as is. This allows the team to visualize potential causes by looking at the changes in the process.
- Fishbone diagram – Also known as a cause-and-effect diagram or Ishikawa diagram, a fishbone diagram allows the team to group potential causes into related categories. The problem being experienced is written as the head of the fish. Each bone on the spine represents a category. Then lines are added to each bone, and these are the potential causes.
Tools for Root Cause Analysis
After identifying the potential causes, the team needs to perform a root cause analysis (RCA). The main idea behind RCA is to eliminate the problem at the root so that it does recur. This is important because it means that resources aren’t wasted on dealing with a superficial or wrong cause.
Here are some popular RCA tools:
- Chi-square test: This is a test performed to determine whether there is statistical significance between the expected and observed outcomes. If the difference is statistically significant, it means an independent cause is responsible. Otherwise, it could be because of chance and not worth further investigation.
- Regression analysis: Regression analysis is a series of statistical techniques that help identify variables that lead to a particular result. In this case, it can help tie which potential causes have an impact on the problem being observed. The team can then know which ones to ignore and which ones pay close attention to, as well as how they are related.
After analyzing the problem, improving it is the next step. This is why the Analyze phase is important, as it helps the Six Sigma team identify the exact cause of the problem at the root. This allows the team to eliminate it once and for all to reduce the incidence of defects.