How to read a source hierarchy in a review article

Not every source answers the same question. For product specifications, original technical documentation or the product itself may be the strongest evidence. For laws or regulatory requirements, the primary government or statutory source matters more than a retailer summary. For scientific claims, the quality and relevance of the underlying research matter.

A source hierarchy is not about automatically trusting one domain. It is about choosing the source closest to the claim being made and being explicit when the available evidence is incomplete.

This also keeps us from using a strong source for the wrong purpose. A manufacturer page can establish what the manufacturer claims, but it does not independently prove every performance claim.

That distinction should be pinned somewhere. “Primary source” does not mean “neutral source”; it means closest to the original claim or record.

Exactly. Source quality and source role are related, but they are not identical.