• Google DoubleClick ad server

Google DoubleClick ad server (Photo : Twitter)

Google reported that slightly over half of online video ads are "viewable." This could explain why online marketers have recently insisted that they will only pay for on-screen ads.

Online marketers insisted that they will only pay for the advertisements that actually appear on viewers' screens, as opposed to sections of web pages that are unseen by users.

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Videos are possibly the most important to marketers. The reason is that video ad inventory prices are relatively high compared to other online ad formats such as banners.

It collected data during April from its various types of video ads and video platforms, including the widely popular Google DoubleClick ad server.

Google learned that just 54 percent of Web video ads are viewable. It did not include YouTube ads, which were a high 91 percent viewable, according to Wall Street Journal.

The difference could be based on YouTube being a Web video destination. This varies from other  websites that locate their video ads beside other content types, or at the bottom of the web pages.

To conduct its study, Google used the Media Rating Council's definition of "viewability." It classifies an ad as viewable if at least half of its pixels can be seen on the screen, for a minimum of two consecutive seconds.

Marketers want to pay only for ads that have the possibility of being seen by web users, such as Google viewable ads. The users do not necessarily have to view all of the ads.

Why were almost half of all web video ads invisible ads? Viewers were typically looking at something else while they played in the background.

Google said that among non-viewable ads, 76 percent were located in the background tab where ads are not showing at all. The other 24 percent were scrolled off the screen or users left them in less than two seconds.

The 54 percent viewability rate in the United States was lower than at least 12 or more nations, according to MediaPost.  They included Japan (83 percent), India (79 percent), and Brazil (76 percent).