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What Are The Tools Of Root Cause Analysis?

Root cause analysis is one of the most crucial problem-solving elements in quality management. Learn everything about the analysis method and its importance to the Six Sigma methodology.

Root cause analysis (RCA) is a process for identifying the root causes of problems and a systematic approach for responding to them. Root cause analysis is based on the idea that effective management should find a way to prevent problems before they occur and affect the work of an entire organization. 

Root cause analysis is one of the most crucial problem-solving elements in quality management. Root cause analysis is an important part of Six Sigma methodology, as it is a key component of the analyze phase of DMAIC – define, measure, analyze, improve, control.

There are six major tools of root cause analysis, which are used through the process of identifying the root causes of a problem.

  • Pareto Chart
  • The 5 Whys
  • Scatter Plot Diagram
  • Fishbone Diagram
  • Failure Mode and Effects Analysis (FMEA)
  • Fault Tree Analysis

1. Pareto Chart

A Pareto chart is a bar chart sorted in descending order from the highest frequency to the lowest frequency from left to right. The height of the bars reflects the frequency or the impact of the problems. The Pareto chart assists the quality improvement team in focusing on areas of improvement with the greatest impact. The Pareto chart is used in Six Sigma to find out the problems and their solutions, and root cause analysis is an important part of that process. To create a Pareto Chart, you can follow X, Y, and Z steps.

2. The 5 Whys

The 5 Whys method uses a series of questions to understand the layers of a problem. The idea is that each time you ask why, the answer you give becomes the fundamental of the next why until you find the sources of the problem. The 5 Whys is a simple tool used for problems where you don’t need any advanced data. This method is used to deeply analyze the results of a Pareto chart used in Six Sigma.

3. Scatter Plot Diagram

A scatter diagram is a two-dimensional graphical representation of a set of data. The scatter diagram graphs pairs numerical data with one variable on each axis to look for their relationship. Its ability to show nonlinear relationships between variables is widely used in Six Sigma. Scatter plots are widely used as a tool for analyzing problems in Six Sigma. Scatter plots show how the variables relate to each other. This relationship is called correlation, and there are three types of correlation: positive, negative, and no correlation. In Six Sigma, a scatter plot will visually display the correlation between a problem and a cause, whether there is positive, negative, or no correlation. This helps quality teams to evaluate which hypothetical cause has the greatest impact on a problem and which should be solved first.

4. Fishbone Diagram

A fishbone diagram, also called a cause-and-effect or Ishikawa diagram, sorts possible causes into various categories that origin from the initial problem. Moreover, a fishbone diagram may have additional multiple sub-causes derived from each identified category. The fishbone diagram is the most used cause-and-effect analysis tool in Six Sigma. The cause-and-effect analysis is one of the key tasks in any Six Sigma project.

5. Failure Mode and Effects Analysis (FMEA) 

Failure mode and effects analysis (FMEA) is a method used to explore potential defects or failures during the process and product design. In Six Sigma, FMEA gives project teams a tool to predict the most likely failures that may impact the customers. The Failure Mode and Effects Analysis is implemented during the analyze phase of the Six Sigma DMAIC cycle, and it helps to estimate the significance of the impact of possible process failures.

6. Fault Tree Analysis (FTA)

Fault tree analysis (FTA) is a graphical tool and one of the more useful tools in Lean Six Sigma problem investigations. FTA explores the causes of system-level failures. Fault tree analysis prioritizes the risks in a way that allows the highest risks to be resolved first. It uses boolean logic to combine a series of lower-level events, and it is basically a top-down approach to identify the component level failures (basic event) that cause the system level failure (top event) to occur. When combined with other Lean Six Sigma tools, fault tree analysis helps the team focus on the most important input variables to the key output variables in a given process. FTA is a top-down approach to identify the component-level failures that cause the system-level failure to occur.

How to Use the Tools in Root Cause Analysis?

Here you can see the ways to use the tools in Root Cause Analysis

  • The Fishbone diagram’s purpose is to identify the many possible causes for a problem and to sort ideas into useful categories. The fishbone diagram should be implemented when the root cause is entirely unknown.
  • The Pareto chart’s purpose is to show which factors are more significant for a problem.
  • The Scatter diagram’s purpose is to help you look for a relationship between two variables. It is a  method of testing correlation between the two variables. To implement this root cause analysis tool, you must plot the suspected cause on the x-axis while the effect is plotted on the y-axis.
  • The 5 Whys purpose is to drill down on a particular problem by asking “Why?” until you identify the core problem. The 5 Whys is best used when implemented with a Pareto Analysis.
  • Failure Mode and Effect Analysis (FMEA) aims to identify different modes in which systems can fail and analyze the consequences and effects of each failure mode. The Failure Mode and Effects Analysis can be implemented during any phase of a particular system - the planning, designing, implementation, or inspection phase, and it helps to estimate the significance of the impact of possible process failures.
  • Fault tree analysis (FTA) purpose is to explore the causes of system-level failures in a top-down approach. You can implement a Fault Tree Analysis in five steps - identify the hazard, obtain an understanding of the system, create the fault tree, identify the cut sets, and lastly, mitigate the risk.

In What Steps Can Tools Be Used During a Root Cause Analysis?

Root cause analysis can be performed in six steps - define the event, find causes, find the root cause, find solutions, take action, verify solution effectiveness. Some of the RCA tools can be implemented during the root cause analysis steps. To define the event and go to the source of the problem, you can use the 5 Whys. To find the potential causes of the event in question, you may implement Fishbone diagrams. To uncover the root cause that lies at the heart of the problem, you can use a Scatter Chart and Pareto Analysis.

Do Root Cause Analysis Tools Have Templates?

Yes, there are root cause analysis tools templates. RCA templates are used to analyze a recurring problem and help eliminate the root causes. Root cause analysis teams drill down to the root of the problem in order to implement solutions so the problem won’t appear again.

  • The 5 Whys template can help ensure that business teams resolve the root cause of problems to avoid them from recurring. This 5 whys template has been designed to make it easier for you to ask and answer the question, “Why?”.
  • The Fishbone Diagram template can be used to explore the potential causes of a particular issue, enabling your team to find a solution more effectively. A Fishbone Diagram template is particularly useful when relying on experience and ideas rather than quantitative data.
  • The Pareto chart template is used to identify and list the problems and their causes. Then, you can score each problem individually and group them together by their cause. This is a clear, visual way to compare various factors contributing to any given problem.
  • A Scatter diagram template can be used to help you find the relationship between respective factors and influences. A scatter diagram charts numerical data pairs with a variable on each axis.

What Is the Importance of the Tools of Root Cause Analysis?

Root cause analysis tools are important in determining and identifying defects and the main causes of defects. By identifying the root cause, the organization can find a permanent solution to it so that possibility of its future re-occurrence can be reduced or eliminated. RCA plays an important role in developing a logical approach to solving problems.

How Do Tools of Root Cause Analysis Improve Work Efficiency?

The tools of root cause analysis are improving work efficiency by detecting and eliminating possible or existing problems at the beginning of a process, system, or production.

Which Sectors Can Benefit from the Use of Root Cause Analysis Tools?

Root cause analysis tools have countless applications in many industries. Here you can see the list of Root Cause Analysis Sectors.

  • Engineering, automotive manufacturing, and industrial process control prevent environmental releases and be utilized for failure analysis in engineering and maintenance.
  • IT and data security, where root cause analysis helps individuals investigate security breaches.
  • Healthcare, where root cause analysis tools are used in environmental science, the medical device industry, occupational safety, and health.
  • Environmental industries, where RCA tools are used to make accident analyses in the aviation and rail industry and prevent their reocurrence.
  • The food and beverage industry to prevent food safety problems and regulatory action by identifying the causes.

In Summary

The main six approaches to root causes analysis are:

  • Pareto Charts
  • 5 Whys Analysis
  • Scatter Plot Diagrams
  • Fishbone Diagrams
  • Failure Mode and Effects Analysis (FMEA)
  • Fault Tree Analysis

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