ISO/IEC 17025 clause 7.2: verification versus validation

What clause 7.2 requires in practice

Clause 7.2 divides method work into two linked parts. Selection and verification (7.2.1) cover choosing suitable methods, keeping them current and available, using the latest valid version where appropriate, telling the customer which method was chosen when they gave none, and proving the laboratory can perform the method before using it. Validation (7.2.2) covers methods that go beyond ordinary use of a published standard: those developed by the laboratory, those that are not standard, and standard methods used outside their scope or modified.

Around these sit planned method development with periodic review, tightly controlled deviations, reassessment when a validated method changes, and retained records. The key distinction is that verification confirms the laboratory can meet the established performance of a method, while validation establishes that a method is fit for a particular purpose. Both lead to records that a competent reviewer can follow.

7.2.1: select a suitable method and demonstrate performance

The laboratory needs appropriate methods and supporting information, kept current and available to the people doing the work. Use the latest valid method version unless that is not appropriate or possible. When the customer has not specified a method, select a suitable one and communicate it.

Before introducing a method, verify that the laboratory can perform it to the required performance and retain the records. An issuing body's revision may require repeat verification to the necessary extent. Method development needs planned work, competent people, resources and review against the customer's needs. Deviations require technical justification, documentation, authorisation and customer acceptance.

7.2.2: validate the intended application where required

Validation applies to non-standard and laboratory-developed methods, as well as standard methods used beyond their intended scope or otherwise modified. Its extent must suit the application. Identify the relevant performance characteristics and establish whether the evidence supports the intended use.

Changes to a validated method need assessment for their effect on the original validation, with further validation where necessary. Keep the validation approach, requirements, performance findings and conclusion about fitness for use. A general declaration that a method is “validated” is weak if the applicable matrix, range or purpose is unclear.

How to make the decision in practice

Begin by defining what the method is intended to do. Consider the sample or item, relevant range, decision to be supported and required performance. Compare that intended use with the method's established scope and identify modifications. This helps the team decide what evidence is needed before it starts generating data.

Sterling recommends planning the work with acceptance criteria and assigned technical responsibility. Evaluate results against those criteria and document limitations. Do not select only favourable data after the exercise or presume that a published method removes the need to demonstrate local capability.

Why clause 7.2 matters to the laboratory

Mistakes in this area are hard to see from the outside. A result produced with a method the laboratory has never shown it can perform, or stretched to a new material, can look perfectly normal and still be wrong. Customers rely on the method being right for their sample and purpose. Clear thinking about verification and validation prevents two opposite errors: spending effort validating something that only needs verifying, and skipping evidence for something that needed more than a published reference. It also helps with commercial decisions about which new services are realistic, and it gives assessors a straightforward story when they ask why a particular range or matrix appears in the laboratory's scope.

How to implement clause 7.2

Use a simple decision path so the same question is asked about every method.

1. Keep a method list showing for each method its source, current version and the range and item types it covers.
2. Create a short intake question for any new or changed method: is it used exactly within its stated scope, or is it modified, extended or developed in-house?
3. If used as published, plan verification against the performance the application needs, with acceptance criteria written before the work.
4. If modified, extended or in-house, plan validation with a defined intended use and the characteristics that matter to it.
5. Assign each plan to a named competent person and approve the conclusion before the method is released for customer work.
6. Re-run the decision whenever the issuing body revises a method or the laboratory changes a step, calculation or tool.
7. Store the plan, data and conclusion together and link them to the controlled method document.

Manufacturing example: a new material matrix

Construction example: a changed preparation stage

A construction materials laboratory proposes a faster preparation step to improve turnaround. The revised step changes the method rather than merely its administrative scheduling. Before adopting it, the team evaluates its effect on fitness for use and applies the relevant authorisation and customer arrangements.

A commercial deadline should not substitute for technical evidence. The resulting records should explain what changed, why the evaluation was appropriate and what the results support. This example does not assume that every change invalidates a method; it shows why the significance must be examined.

Software example: an automated calculation

A laboratory introduces software that processes instrument output and calculates the reportable result. The underlying measurement method may be unchanged, but the laboratory still needs to check the calculation and data interfaces under applicable data-system controls. If the automation changes the method's technical application, that effect also needs assessment.

Use representative and challenging cases, including expected boundaries and exceptions. A software supplier's general assurance does not demonstrate that the laboratory's configured workflow produces correct results for its intended use.

Evidence and frequent misunderstandings

Assessors may examine method versions, selection decisions, verification records, validation plans and results, competence, changes and customer communication. Check whether conclusions are supported by data and whether restrictions are carried into operational instructions.

• Do not call every method exercise validation without explaining its purpose.
• Do not confuse instrument calibration with method verification.
• Do not assume a standard method is suitable outside its stated application.
• Do not omit the effect of changes on previously established performance.

Explore each numbered part

Common nonconformities with clause 7.2

Findings usually come from blurred language rather than missing effort.

• Verification and validation are used interchangeably, so the records do not show which question was answered.
• A standard method is applied to a new material with no assessment of whether its scope still fits.
• A revised edition of a method is adopted by swapping the document, with no check on its effect on performance.
• Validation records exist but say only that the method passed, without the intended use or limits.
• Changes to preparation steps or calculations are made without considering the earlier validation.