APS TO VERIFICATION · FREE INTRODUCTION
Verification and validation: what does the evidence show?
Verification checks specified requirements. Validation also establishes that those requirements are appropriate for the intended use.
1 · Understand APS → 2 · Understand verification
Understand the distinction, recognise the limits of a short study and see how APS guides the judgement.
By Stephen MacDonald · Updated 2 October 2026
Two connected questions
Verification: is there objective evidence that the specified requirements have been met? In a laboratory, this often includes checking established performance claims under local conditions. [1]
Validation: are the requirements met and suitable for the intended use? Reproducing a claim does not settle that second question if the claim does not address your application. [2]
This is why understanding APS comes first: the laboratory needs a reason for the requirement it uses to judge the evidence.
The intended use sets the boundaries
Start with what the method will measure, the specimen type and how the result will be used. Then consider what the existing evidence already covers and what must be demonstrated locally.
An established commercial method used as intended and a modified method may need different evaluations. Changing the specimen, procedure or application can create gaps in the existing evidence. The scope of the work follows those gaps and the applicable requirements; a label such as “verification pack” does not decide it. [3]
A precision study is only part of the picture
A precision study addresses variation under the conditions studied. It cannot establish every other property of a method. CLSI EP15 covers verification of precision claims and estimation of bias; it is not a complete validation protocol. [4]
Method comparison supplies different evidence: differences between procedures across the samples studied. A comparator is not automatically a reference procedure, and agreement does not establish that both methods are correct. [5]
Depending on the intended use, other relevant questions may concern interference, measuring interval, detection capability or specimen effects.
The example continued: what can we conclude?
Fictional example. The assay introduced in the APS guide is used near a low decision threshold. Its precision results are from higher concentrations, and its comparison samples mostly lie in the middle of the measuring interval.
The studies provide evidence for the regions examined. They do not establish performance near the threshold. “Acceptable across the whole application” would go beyond the evidence.
The lesson: identify the unanswered question before choosing additional work. A larger study is only useful if it addresses the relevant gap.
A defensible conclusion has limits
Set the requirement and the approach to judging it before collecting data. Results close to a limit may be inconclusive because study estimates themselves have uncertainty. An unfavourable result needs investigation; repeating until a study passes is not a defensible approach.
The conclusion should say what the evidence supports, what remains unresolved and any restrictions on use.
Routine IQC, EQA and review after changes then provide continuing evidence. Introducing the method is not the end of evaluation. [1,3]
Prepare your planning discussion
The free verification preparation pack helps you describe your question and organise an initial discussion. It contains an editable Word sheet and a completed fictional PDF example.
No payment or account is required. Newsletter sign-up is separate. This introductory aid does not contain a full study protocol or analysis workbook.
Ready to apply the ideas?
The next level is designing a study, analysing its data and writing a defensible conclusion. Planned paid learning will bring these together through guided cases, datasets and editable working documents.
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Continue with the related questions
- Revisit APS: what quality is needed?
- Understand what method comparison shows
- Understand routine IQC
- Understand EQA evidence
You should now be able to explain why reproducing a performance claim and demonstrating fitness for an intended use are connected, but different, judgements.
Sources and boundaries
- [1] JCGM VIM: verification. Definition and notes.
- [2] JCGM VIM: validation. The link to intended use.
- [3] CLSI EP19: framework for evaluating medical laboratory test methods.
- [4] CLSI EP15: precision verification and bias estimation.
- [5] CLSI EP09: measurement procedure comparison and bias estimation.
CLSI links provide public overviews; consult the full applicable guidance for procedures. This introduction and its fictional example do not replace a locally approved protocol or establish compliance.
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