Last Updated on September 25, 2025 by Melissa Lazaro

Root-Cause Analysis for Non-Conformities: Using the 8D Method

If you’ve ever written a corrective action just to satisfy an auditor—or worse, recycled the same response from last year—you’re not alone.

In many labs and PT provider environments, nonconformities are treated like paperwork problems. Something goes wrong, and we patch it up just enough to move on. But here’s the catch: If you don’t understand the root cause, it’s going to come back. And when it does, it’s more than frustrating—it damages credibility with your clients, your team, and your accreditation body.

That’s why the 8D method is a game-changer. It gives you a structured, logical, and proven way to identify what really went wrong, fix it properly, and prevent it from happening again. In this article, I’ll walk you through what the 8D method is, why it works so well in ISO/IEC 17043 and ISO/IEC 17025 systems, and how to use it effectively—without turning it into a box-ticking exercise.

What Is the 8D Method and Why Use It in Labs?

Originally developed by Ford Motor Company, the 8D method—short for “Eight Disciplines”—was designed to address complex problems using a team-based, structured approach. Over time, it’s become a widely adopted root-cause analysis method in manufacturing, engineering, and yes, even in laboratory quality systems.

So why does it work so well for conformity assessment bodies?

Because it:

• Forces you to dig deep into problems—not just symptoms
• Encourages collaboration across departments
• Aligns perfectly with ISO’s corrective action requirements
• Shows auditors that you have a mature, evidence-based approach to continual improvement

In my experience, labs that adopt 8D as part of their QMS see fewer repeat nonconformities and stronger confidence from assessors.

The 8D Breakdown: What Each Step Looks Like

Let’s walk through each of the eight disciplines in real-world terms, not just theory.

D1 – Build the Right Team

Pull together a team that understands the process affected—not just QA staff. Include someone who saw the issue firsthand, someone technical, and someone with decision-making authority.

D2 – Describe the Problem Clearly

Don’t be vague. A strong problem statement includes what happened, where, when, and what the impact was. Use data, audit findings, or complaints to ground your description.

Example: “In Round 02-2024, ten percent of participants received the wrong instruction sheet due to an uncontrolled template used during dispatch preparation.”

D3 – Apply Interim Containment

While you’re investigating, what immediate action are you taking to prevent further impact? That could mean isolating affected items, issuing a participant notice, or temporarily halting a step in your process.

D4 – Identify the Root Cause

This is where most teams either shine—or fail.

Use tools like:

• 5 Whys to peel back layers
• Ishikawa (fishbone) diagrams for broader brainstorming
• Process mapping to identify breakdowns

Avoid stopping at “human error.” Keep digging until you find a systemic issue—usually in documentation, training, communication, or control.

D5 – Implement Permanent Corrective Actions

Once the root cause is confirmed, determine what change eliminates the problem at the system level. That might mean updating an SOP, changing a form, adjusting software access, or introducing a new validation step.

D6 – Verify the Fix Worked

This is one of the most overlooked steps. Don’t just implement a fix—check if it worked.

You might:

• Review data from the next PT round
• Conduct an internal audit
• Monitor trend logs for recurrence

D7 – Prevent Similar Issues Elsewhere

Apply what you’ve learned. If the error could happen in another department, system, or step—share the solution. That’s real continual improvement.

D8 – Recognize the Team

This isn’t fluff. It’s about reinforcing a culture where solving problems is rewarded. Whether it’s a quick thank-you or a formal mention, acknowledging people matters.

Why 8D Aligns So Well with ISO Standards

Let’s connect the dots.

Both ISO/IEC 17043:2023 and ISO/IEC 17025:2017 require that corrective actions:

• Address the root cause of nonconformities
• Are proportional to the risk
• Are verified for effectiveness
• Contribute to improvement

8D does all of that in one structured approach.

Real-world example:
A PT provider I worked with kept getting repeat findings about unclear statistical methods. After switching to 8D, they identified that the real issue was poorly defined responsibilities between the technical and QA teams—not just the documents. They restructured their scheme planning workflow, updated procedures, and retrained staff. In the next assessment? No findings.

How to Document an 8D Investigation (Without Creating a Monster File)

Keep it simple but structured. A solid 8D report includes:

• Problem statement with evidence
• Team members involved
• Notes for each D1 to D8 step
• Corrective action implementation details
• Effectiveness verification records
• Preventive action summary

Pro tip: Use a one-page summary or a fillable template. Your goal is traceability and logic—not paperwork for the sake of it.

Pro Tips for Effective 8D Investigations

• Pro Tip: Always validate the root cause with data or evidence. Avoid guessing or assigning blame without proof.
• Pro Tip: Stop the “5 Whys” once you reach a system-level cause—not just “someone forgot.”
• Pro Tip: Maintain a log of all 8D reports and review them quarterly to identify repeat causes.
• Pro Tip: Ask a team member outside the process to review your draft 8D—they’ll often spot gaps or weak conclusions.

Common Mistakes That Undermine the Process

Treating 8D like a form to fill

If you’re rushing through the steps to get it over with, you’re missing the point.

Jumping straight to a solution

Skipping root cause analysis leads to band-aid fixes. The problem will return.

Only blaming human error

Operator mistakes are symptoms. Dig until you find what made the error possible.

Forgetting to verify

Fixing a problem is one thing—making sure it stays fixed is another.

FAQs

Q: Is the 8D method required by ISO?
No—but it fulfills ISO’s corrective action expectations brilliantly. Auditors like it because it’s structured, logical, and repeatable.

Q: Can we use 8D for minor nonconformities too?
Yes, just scale it down. A smaller team and lighter documentation still follow the same thinking process.

Q: What if we can’t identify the root cause?
You probably need fresh eyes. Bring in someone outside the process, or use a different tool like a process map or fishbone diagram.

Don’t Just Correct—Understand and Improve

When you stop treating nonconformities as tasks to close and start treating them as opportunities to learn, your QMS becomes something powerful. It becomes a system that evolves, strengthens, and earns real trust—from your team, your customers, and your accreditation body.

The 8D method helps you do that. It gives you the clarity, structure, and credibility to move from quick fixes to real solutions.

Want a ready-to-use 8D template? I can send one your way—along with a mini-guide to walk your team through their first 8D session.

Let’s stop guessing. Let’s start solving.