According to second quarter findings from AdSafe Media, perhaps. The ad verification service provider found that less than half of the ads worldwide purchased on ad exchanges, networks and publisher sites that passed through its system were in-view.
Ads bought direct from publisher sites were in view the greatest percentage of the time. AdSafe Media defined in-view impressions as any impression that had 50% or more of the ad unit visible for one second or more. Note that after 15 seconds, just 21.1% of all publisher impressions were considered in view, compared to about 16% of ad network and exchange-purchased inventory. Read the rest at eMarketer.