Why Is Mobile App Ad Viewability So Hard To Measure?

Because of in-app ad spend's recent surge, getting accurate in-app viewability measurements is a big deal for mobile marketers. We forecast that $77.03 billion will be spent on in-app advertising in the US this year, up 25.1% over 2018.

A recent PubMatic and Forrester Consulting survey of decision-makers at brands and agencies revealed widespread concern with viewability measurement of programmatic in-app advertising. Among brand respondents, only fear of fraud ranked higher as a key challenge. Viewability measurement was the top challenge, for agency respondents.

“Mobile campaigns are run across mobile web and app, without splitting them out,” said Paulina Klimenko, general manager of mobile at supply-side platform (SSP) PubMatic. “Because verification methods for the browser vs. in-app environments are so different, the [in-app] viewability signals delivered by vendors to advertisers are often inaccurate.”

On desktop and mobile web browsers, measurement companies can track viewability by deploying a pixel on the website they're analyzing. With mobile apps, measuring viewability requires the use of software development kits (SDKs)—software tools that allow third parties to integrate their products into apps. To track viewability within apps, third-party measurement companies have to get app owners to install their SDKs, according to Jane Clarke, CEO of advertising trade group Coalition for Innovating Media Measurement (CIMM).

“This is a huge hurdle, because these companies usually subcontract app development to outside developers that often live in different countries, and the lawyers at the app owners must ensure that the SDKs are in compliance with consumer privacy laws,” Clarke said. “Additionally, every time an app is updated, the SDK has to be tested to make sure it still works.”

Another roadblock is that each SDK they adopt increases the size of their app, creating latency. Android apps have 18.2 SDKs on average, according to SDK management firm SafeDK.

If a publisher decides to not integrate a measurement vendor’s SDK, then the vendor and its marketer clients will struggle to accurately measure the app’s ad viewability. In April 2018, the IAB Tech Lab made its open measurement SDK widely available in an attempt to help alleviate this issue. The open measurement SDK includes viewability trackers from multiple vendors, allowing publishers to adopt a single standardized SDK for viewabilty instead of having to integrate an additional SDK for each vendor. Nineteen companies have gone through IAB’s SDK certification program, according to an IAB spokesperson.

Viewability also impacts how campaigns get billed because many advertisers use their programmatic buying platforms to restrict media spend to inventory that is highly viewable. With viewability metrics becoming so consequential to advertisers, disagreements have arisen over how they should be defined and measured.

The CMO Council surveyed 233 senior marketers worldwide in Q1 2018 and found that few respondents completely agree with the IAB’s viewability guidelines, which consider video ads viewable as long as 50% of the ad is on screen for at least 2 consecutive seconds. About four in 10 respondents said they disagree with the industry standard, but admitted they struggled to find a better definition.

CMO Council's study indicates that disagreeing with the status quo is easy, but finding solutions remains elusive.