"Their page RPM crushes mine"

"Their page RPM crushes mine"

Fair: page RPM is a clean per-unit number, and theirs is genuinely higher.

But page RPM rewards sites that ration pageviews. A site with 1.3 pages-per-session and heavy ads per page posts a gorgeous page RPM and a mediocre session RPM. A site with 3.5 pages-per-session and lighter pages looks worse per page but earns far more per visitor. You're comparing the wrong unit, so the "winner" depends on which metric flatters whom.

🚩 Hidden variable: pages-per-session linking the two metrics. Page RPM and session RPM can rank two sites in opposite order.

Session RPM is the visitor-level truth. Page RPM is what people quote when their pages-per-session is low and they need a flattering denominator.

Not saying page RPM is useless — saying the comparison is rigged.