5 Why vs. Pareto Chart vs. Fishbone Diagram – Pros and Cons of Each of These RCA Techniques
Blog | August 24th, 2022

5 Why vs. Pareto Chart vs. Fishbone Diagram – Pros and Cons of Each of These RCA Techniques

All Quality Management Standards emphasize the importance of identifying the root cause of any problem – to address it more effectively and find a lasting solution to prevent its recurrence.

Often, there may be a surface-level reason for an issue, and in a rush to meet deadlines and other commitments, the root cause may be missed and only a reactive solution gets implemented. This will lead to the problem festering and recurring, sometimes with greater severity. By conducting a well-designed root cause analysis (RCA) process, enterprises can get to the “root of the problem”, and approach it systematically with the goal of finding a long-lasting solution.

Let’s take the example of a quality issue at a manufacturing company. There was an issue with a certain batch of products not meeting the required specifications. The quality team, after conducting a quick RCA, spotted two issues. One, lack of proper equipment maintenance resulting in faulty production, and two, a supplier issue where one of the parts didn’t meet specs. Both issues were solved, yet the problem kept resurfacing. Eventually, the quality team conducted an RCA using the 5 Why framework. The root of the problem revolved around the lack of proper training wherein the equipment settings had to change depending on the product being manufactured.

Root cause analysis helps “with defining, measuring, analyzing, improving, and controlling problems” – all with the goal of delivering continuous improvement of all quality management processes.

There are several kinds of root cause analysis techniques. These include:

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

In this blog, we will compare and analyze Pareto Chart, 5 Whys, and Fishbone diagram and discuss their pros and cons as a root cause analysis method.

Comparing the Pros and Cons of Pareto, 5 Whys, and Fishbone Methods of RCA for Driving Quality Performance

What Is a Pareto Chart: A Pareto chart represents the frequency or the impact of problems in descending order from left to right in the form of a bar chart. This helps the quality team identify problems that need attention on priority. It works on Pareto’s law that lays down the 80/20 rule, where 20% of inputs are known to cause 80% of the results.

5 Why: In the 5 Why method, the question ‘why’ is asked repeatedly at every level, helping to dig deeper and identify the true cause of an issue. It is a simple tool and doesn’t need advanced data. This further enhances the understanding derived from the Pareto chart.

Fishbone Diagram: A fishbone diagram is also known as a cause-and-effect or Ishikawa diagram. It helps to categorize the suspected causes and can be subdivided into multiple levels, going deep into the problem.

Application of the Three RCA Techniques in Quality Management

If a problem has many root causes, the Fishbone diagram, and 5 Whys can help to unearth them.

While Fishbone enables grouping them into different categories, 5 why helps to dig deeper into each root cause. The 5 Whys method is especially useful when there is no evident root cause, while Pareto helps to grade the known causes and prioritize the response to each.

Fishbone and 5 Why also allow links to be established between different events and their causes, which helps to identify the appropriate, meaningful, and impactful solution. The two can also be used together to visualize the several causes of a problem and organize them for further analysis and data gathering.

Fishbone is especially useful in facilitating collaboration between the different stakeholders, representing their ideas visually, stimulating and broadening thoughts on the causes and their solutions, and coming to a consensus.

The 5 Whys can enhance the impact of these insights by allowing every cause to be drilled down further. Pareto can help with prioritizing the causes and addressing each in the order of severity for continuous improvement.

Pros and Cons of the 3 RCA Techniques

Below is a table providing the advantages and disadvantages of the three RCA techniques.

Technique Advantages Disadvantages
Pareto
  • Identify and determine the main cause by ranking them in the order of their severity
  • Helps prioritize solution-identification
  • Assess the cumulative impact of a defect over a long period of time
  • Improves problem-solving skills of the team
  • Represents only qualitative data that cannot be quantified. So, assessing severity is a challenge
  • Focuses on past data after the damage has already happened. This may be irrelevant to predict future scenarios
  • Its application is limited to some situations only
5 Whys
  • It is simple, elegant, and easy to apply
  • Discovers deeper issues rather than assign blame
  • Helps to identify solutions
  • Facilitates collaboration for continuous improvement
  • May be too basic
  • Depends on the capability of the investigator or investigators
  • Results may be subjective and cannot be replicated
  • May be effective for simple problems only
Fishbone Diagram
  • Determine the cause-and-effect relationship between problems and processes
  • Facilitate collaboration for problem-solving
  • Generate innovative solutions
  • Risk of digression and confusion due to accommodating too many ideas
  • Can become complicated due to handling multiple factors
  • Categorization and subcategorization can add further complexity, making the problem larger than it is

The three root cause analysis methods are very useful in providing insights into the root cause, the relationship between the different causes, the root cause that needs to be addressed first, and in enabling collaboration for finding an effective solution. It can help with triggering CAPA to address the current issue and prevent future issues. But each has its own limitations and may be effective together.

Manually handling RCA can add further complexity as keeping track of the path the discussion takes can be difficult. Automated workflows using the ComplianceQuest enterprise-wide quality management system can help with making the RCA effective and efficient.

The CQ solution provides a 5 Why analysis tool that allows collaboration between different team members, communication, monitoring, tracking, and following up on the action taken. This improves the effectiveness of RCA and ensures that the purpose of eliminating the root cause is achieved with minimum complexity and confusion. All documents from both Pareto and Fishbone processes can also be uploaded to CQ Document Management Solution.

Overall, CQ EQMS is an ideal tool for automating and streamlining the end-to-end RCA process, using any or all of these methods.

To know more about how ComplianceQuest can help you with your CAPA and RCA process, visit: https://www.compliancequest.com/capa-management-software/

Request a demo here: https://www.compliancequest.com/lp/eqms/

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