Root Cause Analysis Tools: Find and Fix the Real Problem

What Is a Root Cause Analysis Tool?

A root cause analysis (RCA) tool helps you trace a problem back to its source. Instead of fixing what’s visible (the symptom), RCA digs into the underlying reason it happened in the first place. It’s how smart teams solve problems once, not repeatedly.

What Are the Most Common RCA Tools and Techniques?

These are your go-to RCA tools:

• 5 Whys: drill down by asking "why" until you reach the core issue.

• Fishbone Diagram (Ishikawa): map out possible causes by category.

• Pareto Chart: focus on the biggest impact problems first.

• Scatter Diagram: visualize variable relationships.

• Failure Mode and Effects Analysis (FMEA): identify risks and prioritize them.

• Fault Tree Analysis (FTA): a logic-based map from problem to root cause.

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 pair 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 a 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 originate 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 analysis 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 events) that cause the system level failure (top events) 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 identifying the component-level failures that cause the system-level failure to occur.

How to Implement RCA Tools in Your Organization?

Here’s the fast-start root cause analysis implementation checklist:

1. Define the event: What happened?
2. Find possible causes: Use Fishbone or brainstorming.
3. Ask Why: Run a 5 Whys session.
4. Validate: Use data or a Pareto Chart.
5. Fix: Build and ship the solution.
6. Follow-up: Did the fix take hold? Measure it.

Bonus: Utilize templates (Fishbone, 5 Whys, Pareto) to expedite the process and establish consistency.

How to Use the 5 Whys Technique in Root Cause Analysis?

Simple: Ask “Why?” five times.

Example:

1. Why did the machine stop? Because it overheated.
2. Why did it overheat? Because the coolant pump failed.
3. Why did the pump fail? Because the motor burnt out.
4. Why did the motor burn out? Because it wasn’t maintained.
5. Why wasn’t it maintained? Because the PM schedule wasn’t followed.

Now you’re not fixing a machine. You’re fixing a broken process.

What Is a Fishbone (Ishikawa) Diagram and How Is It Used in RCA?

The Fishbone diagram resembles a fish skeleton. The "head" is your problem. The "bones" are categories of potential causes (e.g., People, Process, Machine, Materials).

Use it when:

• You need to brainstorm broadly.
• You want to group causes visually.
• You’re working with a team.

It’s perfect early in the RCA process to ensure you’re not missing significant causes.

What are the benefits of using root cause analysis tools?

• Fewer recurring problems: fix it once, not five times.

• Smarter process improvements: data over guesses.

• Better team alignment: everyone sees the same logic.

• More predictable quality: better outcomes, fewer surprises.

• Stronger customer trust: fewer errors mean better service.

RCA tools don’t just solve problems—they help teams learn from them. That’s what makes improvement sustainable.

Can RCA Tools Integrate with Your Existing Workflows?

Yes. RCA tools are integrated into quality management platforms or project management software. Integrations include lean portfolio solutions such as Businessmap (formerly Kanbanize), continuous improvement software like KaiNexus, or Excel sheets and custom templates.

What features should I look for in root cause analysis software?

You want tools that make RCA easier, not harder. Look for:

• Templates: built-in Fishbone, 5 Whys, FMEA, etc.
• Collaboration: teams can contribute in real time
• Tracking: measure recurring issues and outcomes
• Integration: plug into your PM or QMS stack
• Exporting: share results with stakeholders