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Is Less Viewable Mobile Ad Inventory Actually More Valuable For Brand Marketers?

Contrary to popular belief, viewability rates in mobile advertising might not be the end-all, be-all metric for advertisers and agencies. On mobile sites, optimizing for high viewability can lead to a higher likelihood of a consumer actually seeing an ad, but our research indicates that high viewability doesn’t necessarily lead to higher time spent or viewable click-through rates (vCTRs).


With the Media Rating Council (MRC) recently releasing guidelines on mobile viewability in June 2016, more agencies and advertisers are starting to leverage viewability as a key ad effectiveness metric. Some (e.g., GroupM) have shifted entirely to transacting on viewable impressions served, rather than total impressions served.


However, we’ve anecdotally observed that mobile viewability metrics can be ambiguous as they relate to ad effectiveness and typical advertiser key performance indicators (KPIs), such as viewable click-through rate (vCTR) and conversions. Does high viewability drive higher vCTRs and/or conversions? Compounding that ambiguity, one viewability rate can have different meanings to different constituents. For example, marketers and publishers still do not agree whether the current definition of viewability (50% of the ad area in view for one continuous second) properly represents how marketers are trying to achieve their KPIs. This debate on viewability standards exposes that it’s difficult to reach consensus on exactly what viewability is measuring in terms of ad effectiveness.


Given this challenge, the Testing & Insights team at Yieldmo set out to understand viewability across our advertising and publisher partners to understand what viewability means, as well as if and how it connects to other ad effectiveness measurements.


We analyzed 57,206 publisher placements, comparing “placement on page” (i.e., distance from the top pixel of a mobile website*) with the following key metrics:


Viewability rate (i.e., the percentage of impressions in which the ad was “viewable” according to Yieldmo’s definition of viewability, which is 100% of the ad in-view with no time minimum)

Time spent (i.e., exposure time with viewable ad in seconds)

Viewable click-through rate (vCTR)


*Note: These placements excluded interstitial and adhesion units.


So, what did we find?



First, viewability is correlated to vertical page placement. The highest average viewability levels (approximately 60-70% viewability rate) were found to be 20-30% from the top of the mobile pages and the lowest average viewability levels were found to be at the bottom of the mobile pages. This was no surprise, as mobile users start at the top of the page and always work downwards.


Second, and related to the first point, consumers spend considerable time on “non-viewable” page sections. Users spent more time in areas where the viewability is lower than 50%, such as the footer section of the page. In fact, significant time is being spent in areas in the 30-50% viewability range, a range in which many brand marketers typically avoid when buying inventory. This was more of a surprise than the first point, as we tend to think that high viewability equates to time spent on a page. However, we believe that as mobile users drift down the page, they tend to skim lower portions of the article and look for their “next step,” which might be another article or a product or brand message (in the form of an ad).


Thirdly, we found that high viewability doesn’t mean high time spent and vCTR. While viewability _is_ correlated to page placement (vertical location of an ad on a mobile site) — meaning viewability rates are higher in upper sections of the mobile page — time spent and vCTRs are far less correlated to viewability and placement location. In fact, those that insist on 90% viewability and above may be overpaying based on the time and attention being spent in these areas.


Finally, vCTR tends to increase as viewability rates decrease. In sections of the mobile page with 5-10% viewability rates (typically at the very bottom of mobile pages), vCTRs are 3-5x higher, compared to sections of the page with viewability rates of 50% or higher.


What does this mean for brand agencies and advertisers?


Viewability is important for brand campaigns. For agencies and advertisers looking to create brand awareness and favorability on premium publishers’ mobile sites, viewability is an important metric to determine whether an ad has the opportunity to be seen by a consumer. Those media buyers should target premium publisher mobile sites to achieve high viewability rates.


However, depending on marketing objectives and desired KPIs, viewability is not always the right metric to optimize for. For agencies and advertisers looking to optimize for time spent or vCTR, viewability might not be the best metric to focus on. Instead, those media buyers should develop strategies around page placement and work with mobile inventory providers that have ad placement optimization algorithms.


What’s next?


We think that viewability is undoubtedly critical to understanding advertising success. In the coming weeks, we will continue to analyze our wealth of mobile impression and engagement data to better understand which mobile metrics are most important for advertisers and agencies.


Stay tuned for our next analysis!
Posted by: Jane Kim, Head of A/B Testing & Optimization