Different Tests Answer Different Questions.
A quality assessment can examine label accuracy, ingredient identity, or selected contaminants. NSF describes its supplement certification program in terms of label-claim, toxicology, and contaminant reviews, with continuing audits and retesting. These are defined activities within a particular program. [Source]
Read the Scope.
Ask what was tested, which sample or product the result concerns, and what conclusion the document actually states. Avoid filling in missing details. A broad phrase on a webpage gives less information than a clearly identified test and its context.
Separate Quality From Health Outcomes.
As a matter of interpretation, a finding about an ingredient or its amount answers a composition question. It is not, by itself, a clinical study showing how the complete formula affects people. Keep the question about contents separate from the question about a health benefit.
Check a Certification at Its Source.
If a product carries a certification mark, use the certifier’s own product listing to check the exact item and program. NSF provides public listings for its certified supplements. Reading about a program does not mean every product discussed on the same website belongs to it. [Source]
A useful testing statement tells you what was examined and how far the result reaches.