Ask four questions
First, was the test material a raw ingredient or a finished product? Second, was the work done in people or in a laboratory model? Third, what was it compared with? Fourth, what changed—and how was that measured? Keep those answers next to the claim, rather than hiding them in a footnote.
Use a real study as a reading exercise
The niacinamide study linked below explicitly describes its test concentration, a control vehicle, a split-face design, and the study duration. Those details let you assess how closely a claim matches the experiment. They do not identify the performance of an unrelated commercial serum. [1]
Keep unknowns visible
If concentration, formulation, or product-specific testing is not provided, record it as unknown. “Contains an ingredient studied for X” and “this product was shown to do X” make different claims. Our formula examples use the first kind of description unless appropriate finished-product evidence is available.
A brand ingredient list answers what the brand declares is in a formula. It does not replace an independent test, and a customer review is not a clinical trial.
A common question
What does a source link prove?
Only what the linked source actually supports. A citation must match the specific statement, not merely discuss the same topic.