View-through conversion

A view-through conversion says: this person was served your ad, did not click it, and later converted, so the ad gets credit.

The idea is not absurd. Advertising works partly by being seen, and a model that only counts clicks undercounts display and video, where the click is a poor proxy for attention.

But the evidentiary bar is low, in a way that compounds. A view usually means the ad was rendered and technically viewable — not that anyone registered it. Serving a lot of cheap impressions to a large audience guarantees that some of them convert for unrelated reasons, and every one of those becomes a view-through conversion. The more impressions you buy, the better the channel appears, regardless of whether the advertising did anything.

Three things to check before believing one.

• The window. View-through windows are usually much shorter than click windows, for good reason. If yours is not, the channel is claiming credit for things that happened days after a glance.
• The overlap. View-throughs frequently sit on top of people who also clicked something else. Reported side by side, the same conversion gets counted twice in two different reports.
• The direction of the incentive. The party crediting the view-through is the party selling the impressions.

Treat them as a directional signal, never as a line item you would defend to a finance team. The way to find out whether impression-based advertising works is to turn it off for a comparable group and see — which is incrementality, not a view-through report.