Optimization glossary

Ad viewability

What is ad viewability?

Ad viewability is the concept of how visible ads on a website or mobile app are to users. For an ad to be considered “viewed” at least 50% of the banner or creative must display on screen for more than one second, as defined by the Internet Advertising Bureau’s (IAB) standard for what consists a viewable impression.

Why is ad viewability important?

Ad viewability is a relatively new concept in digital advertising, but has become a hot topic ever since a report from comScore showed that 54% of display ads were not being seen, despite advertisers paying for them.

In the early days of Internet advertising, ad networks emphasized the number of ads served, rather than the number of ads viewed, and the metrics reported on ad campaigns were traditionally on the number of ads served.

Marketers would calculate the relative success of a campaign by dividing the number of ads served by the number of clicks. This gave the ultimate digital advertising metric: the clickthrough ratio, or CTR.

Over time as online advertising matured, however, advertisers began to question the practice of using ads served as a proxy for ads viewed. For example, it occurred to them that if an ad appeared below the fold at the bottom of a webpage, but a user never scrolled down far enough to see it, that ad was non-viewable and the ad impression should not be counted.

In addition, it became clear that there were other factors that could contribute to an ad not being seen: users clicking away from a page before the ad loaded or bots and proxy servers opening pages, rather than live human beings.

Because of these factors, advertisers are beginning to demand that publishers quantify the percentage of their ads that are actually a viewable ad and structure their advertising rates accordingly. It is important for media companies to ensure that their customer’s ads are viewable so that they can keep their advertisers happy.

How to improve ad viewability

Because there is such a high ROI correlated with improved viewability, it is in the best interest of publishers to prioritize improving the visibility of their ads.

Publishers can begin by designing their pages in such a way that the ads load with maximum viewability potential. This can either mean designing a page so the ad unit is ‘above the fold’ or is a ‘sticky’ ad unit. Sticky ad units are a type of ad that remain locked in a specific location when the user scrolls.

Publishers can also make their sites mobile-friendly by using responsive templates that resize according to the device it is being viewed upon. This guarantees a good user experience no matter the device (tablet, phone or desktop) and has become an industry standard.

Ad viewability also improves through good design principles: a clear visual hierarchy, symmetry, pleasing proportions, white space and clean design.

Another key consideration for ad viewability is speed. Sites that are laden with ads from multiple ad networks can typically take a long time to load, which can result in a lower ad viewability as users click away before the ads load. Techniques for speeding up ad delivery can greatly improve ad viewability.

In addition to activities focused on the delivery of ads, publishers can also begin measuring and validating ad viewability through third party software and making those metrics available to advertisers.

Publishers who want to show that they are ‘playing fair’ can partner with one of 15 Media Rating Council (MRC) Accredited Viewable Display Impression and/or Ad Verification Vendors, all who measure viewability across digital campaigns.

Using A/B testing to improve ad viewability

Viewability data can help publishers increase the value of their display inventory. As advertisers and digital marketing teams seek out publishers with higher viewability rates, publishers with this inventory will benefit. In addition, sharing viewability data will make it easier for brands to compare rates across multiple publishers.

Through its integration with leading viewability analytics platform Moat, publishers who use Optimizely can set up a series of A/B tests where they test page layouts to ensure the highest levels of viewability, ad placement, performance, ROI for digital ad campaigns and content to ensure an ad served results in an ad impression.

Optimizely A/B tests will indicate the high and low areas of viewability on your site so you can learn how to optimize your site and increase ad viewability.