In online advertising there is currently much controversy about charging advertisers for ads that could never be seen by consumers. In November 2014 Google, to their credit, issued a report that showed that only around half of the ads that were served by their servers were ever able to be viewed (e.g. many viewers did not scroll down far enough for it to appear on their computer or smartphone screen). Even more extraordinary, this figure of half the ad ‘impressions’ being (potentially) viewable was based on a very generous definition of “viewable”, that is, that at least 50% of the ads pixels were onscreen for one second or more. Unsurprisingly leading advertisers are calling for higher standards of viewability, in June 2015 Unilever’s Chief Marketing Officer Keith Weed said that only 100% viewability is acceptable, that for an online ad to count as an impression 100% of the ad needs to be onscreen not merely served by the web server to the web browser or app.
Of course Keith’s right, we don’t want to pay for vapourware, but we don’t have to, even if new standards of viewability are not agreed upon we can now easily calculate a figure closer to reality simply by halving the impression score. Or, put another way, double the CPM (cost per thousand impressions).
That gets us much closer to the truth, but not quite there though. Another consideration for online video and display ads is the problem is that some of the impressions that are served, and paid for by advertisers, are not reaching humans. Audience impression figures are inflated by views by other computers (‘spiders’ and ‘robots’) rather than actual humans. Some of this fake traffic is even fraudulent where firms collect money for delivering referrals to web sites, inflating their ratings. Fake clicks and video views can also be generated, often by virus software running on the computers of unsuspecting consumers. Major providers of online advertising space such as Facebook and Google have anti-fraud teams devoted to detecting this activity but it remains a problem. It’s difficult to know how large a problem it is, as many of the people reporting statistics have in interest in over-stating the problem (e.g. firms who sell anti-fraud solutions) or under-stating the problem (e.g. firms who sell on-line advertising space). In November 2014 Kraft is the US reported that it rejects more than three quarters of digital ad impressions deeming them “fraudulent, unsafe or non-viewable or unknown”.
That figure sounds about right given the Google research (others report similar numbers) and the fact that some impressions are non-human.
So about one in four online ad impressions is an actual opportunity to see (OTS) for a real human viewer. However, we can’t assume each ad impression is always actually seen, and therefore able to affect memory, we have to discount for the perceptual filters and inattention of these human beings. This is true for any media, an OTS is an opportunity for our ads to be seen not a guarantee. Just how much this varies by media, and by situation, is something that we are researching now in the Ehrenberg-Bass Institute. It will be some time before we have the solid empirical evidence needed to accurate compare the impact on brains of an OTS in different media. But until then we can still make meaningful comparisons between media at least in terms of the OTS, and a good guide for digital seems to be to quadruple the cost of each impression in order to compare it to another medium.
Professor Byron Sharp
University of South Australia
PS Google Ad Networks have announced that they are about to change bidding for CPM (per thousand impressions) to vCPM, which means you only pay for viewable ad impressions. Unfortunately viewable still merely means “when 50 percent of your ad shows on screen for one second or longer for display ads, and two seconds or longer for video ads”. So an important step in the right direction, now we have something closer to what would count as an OTS (or impression) in other media.
PPS Google suggest that you’ll need to double your old CPM bids now they are using vCPM. This is inline with the research cited at the start of this article.