Method Validation vs Method Verification – Understanding the Difference in ISO/IEC 17025

Method validation and method verification are two terms frequently used in testing laboratories—and sometimes used interchangeably.

They should not be.

Both activities provide confidence that a laboratory method is suitable for its intended purpose, but they answer different questions.

In simple terms:

Method validation asks: “Is this method fit for its intended use?”

Method verification asks: “Can our laboratory successfully perform an established method?”

Understanding the difference is important because performing a few QC samples does not automatically constitute validation, while adopting a published standard method does not eliminate the laboratory’s responsibility to demonstrate that it can perform the method properly.

What Is Method Validation?

Method validation is the process of establishing, through objective evidence, that a method is suitable for a particular intended use.

Validation is generally necessary when a laboratory develops its own method, uses a non-standard method, or uses a standard method outside its intended scope. Significant modifications to an established method may also require validation.

The extent of validation should be appropriate to the intended application.

Depending on the type of testing, validation may evaluate characteristics such as:

• Accuracy or trueness
• Precision
• Selectivity or specificity
• Detection and quantitation capabilities
• Working or calibration range
• Robustness
• Measurement uncertainty
• Potential interferences

Not every method requires every characteristic to be evaluated in exactly the same way.

The important question is:

What evidence is necessary to demonstrate that this method can reliably produce results suitable for its intended use?

What Is Method Verification?

Verification applies differently.

Imagine a laboratory decides to implement a recognized standard method that has already been validated by the organization that developed it.

Does the laboratory need to completely validate the method again?

Generally, no.

But the laboratory still needs evidence that it can properly perform the method before routinely using it for customer samples.

This is method verification.

The laboratory may need to demonstrate that it can achieve required method performance under its own conditions using its:

• Equipment
• Analysts
• Reagents and standards
• Laboratory environment
• Sample preparation processes
• Quality control system

The exact verification activities depend on the method and applicable requirements.

The important point is that a published method is not automatically proven to work successfully in every laboratory simply because it has already been validated elsewhere.

A Simple Way to Think About the Difference

Consider two scenarios.

Scenario 1: A Laboratory Develops a New Method

The laboratory develops an analytical method for a specific application.

Before reporting customer results, it needs evidence demonstrating that the method performs appropriately for that intended use.

That is validation.

Scenario 2: A Laboratory Implements an Established Standard Method

The laboratory adopts a recognized method exactly as intended.

The method itself has already been validated, but the laboratory needs to demonstrate that it can achieve the required performance.

That is verification.

The distinction becomes more complicated when laboratories modify established methods.

A seemingly small modification may affect method performance. The laboratory therefore needs to evaluate the significance of the change and determine whether additional verification—or validation—is necessary.

“We’ve Always Used This Method” Is Not Objective Evidence

One issue I occasionally encounter during laboratory audits is a long-established method with very little documentation showing how its suitability was originally demonstrated.

The explanation may be:

“We’ve been using this method for years and it works.”

Experience with a method is valuable, but it does not necessarily replace documented objective evidence.

Laboratories should be able to demonstrate why a method is appropriate, what performance was evaluated, what acceptance criteria were applied, and what results supported its implementation.

This becomes particularly important when personnel change and the individuals who originally introduced the method are no longer available.

Verification Is More Than Running One QC Sample

Another potential weakness is treating verification as a quick administrative exercise.

A laboratory runs a reference material, obtains an acceptable result, and declares the method verified.

That may or may not provide sufficient evidence.

The verification should be appropriate to the method, its performance requirements, applicable regulatory or accreditation requirements, and the laboratory’s intended use.

The objective is not to generate a verification form.

It is to establish reasonable confidence that the laboratory can perform the method as required.

Documentation Matters

Whether performing validation or verification, laboratories should maintain enough documentation to demonstrate:

• What was evaluated
• Why it was evaluated
• What acceptance criteria were used
• What data were generated
• Whether the results met the criteria
• Who reviewed and approved the work
• What conclusion was reached

A collection of analytical data without clearly defined acceptance criteria or a documented conclusion can make it difficult to determine what the study actually demonstrated.

Good documentation should tell the story from the purpose of the study through the final decision.

One Observation from Laboratory Audits

When reviewing method validation or verification records, one of the most useful questions is:

“What evidence gave the laboratory confidence that this method was ready for routine use?”

A strong response usually leads directly to documented performance data and defined acceptance criteria.

A weaker response often leads to historical practice, individual experience, or a statement that the method is published.

ISO/IEC 17025 is not asking laboratories to create unnecessary studies.

It is asking them to have objective evidence that the methods they use are appropriate and that they can perform them competently.

Questions to Consider

When implementing or reviewing a method, ask:

• Is this a standard, non-standard, laboratory-developed, or modified method?
• Are we validating the method or verifying our ability to perform it?
• Is the extent of the study appropriate for the intended use?
• Were acceptance criteria established before evaluating the results?
• Do the records clearly support the conclusion?
• Have significant method changes been evaluated for their potential impact?

These questions can prevent validation and verification from becoming paperwork exercises.

Key Takeaway

Validation demonstrates that a method is fit for its intended purpose.

Verification demonstrates that the laboratory can successfully perform an established method before introducing it into routine use.

The extent of either activity should be appropriate to the method, its application, and applicable requirements.

Conclusion

Method validation and method verification share the same broader objective: confidence in laboratory results.

But they reach that objective from different directions.

A laboratory developing or significantly modifying a method needs evidence that the method itself is suitable for its intended application.

A laboratory implementing an established method needs evidence that it can achieve the required performance under its own conditions.

Understanding that distinction helps laboratories avoid both extremes—performing unnecessary validation work and assuming that a published method requires no laboratory-specific demonstration at all.

Ultimately, the question is not simply whether the laboratory has completed a validation or verification form.

It is whether the laboratory has objective evidence that the method is suitable and can produce reliable results.