Adding an MD co-author (not just a reviewer): a 50-page YMYL test

Adding an MD co-author (not just a reviewer): a 50-page YMYL test

The question: is there a measurable difference between an expert who reviews content and one credited as a co-author who demonstrably contributed?

A health publisher's documented test: ~50 condition pages were assigned a practicing physician as genuine co-author — quoted original commentary, an 'in my clinical experience' passage, and the physician's verifiable credentials linked. A matched ~50-page control kept the standard staff-writer-plus-reviewer model. Reported outcome over ~5 months: co-authored pages improved an average of 3.1 positions versus 0.9 for the control, with the gap widest on the most competitive head terms.

This touches the QRG distinction between 'expertise' demonstrated in the content (section 3.4) and mere credential-stamping. First-person clinical experience is exactly the 'Experience' that the 2022 addition of the extra E was meant to capture.

Counter-evidence: co-authored pages received more total writing effort and original quotes, which improves them independent of the credential.

Caveat: 'co-author' and 'reviewer' differed in both attribution and content depth here — the variables are entangled. A cleaner test would hold content constant and vary only the labeling.

What we still don't know: whether Google's systems read the difference between reviewed and co-authored, or whether the measured lift is simply the value of an expert actually contributing sentences a layperson could not write.