Everyone treats viewable as the floor. It's the ceiling of a measurement that quit early.

Everyone treats viewable as the floor. It's the ceiling of a measurement that quit early.

Viewability answers "could this have been seen?" It never answers "was it?" An ad can be 100% on-screen behind a reader who's scrolling, multitasking, or about to close the tab. Pixels in the viewport, attention out the window.

The industry knows this — it's why attention measurement exists as a separate category. Viewable is necessary and wildly insufficient.

Treat viewability as a hygiene gate, not a performance metric: filter out the non-viewable, then ignore it and judge inventory on time-in-view and post-click behavior. If you're still reporting viewability as a success KPI to a client, you're grading the test on whether the paper was handed out.