Google+ found when visitors of mobile website were presented with an app install interstitial, 69% abandoned the page; user retention spiked after removing it
Google+: A case study on App Download Interstitials — Many mobile sites use promotional app interstitials to encourage users to download their native mobile apps.
Context & Ripple Effects
Google spent spring 2015 pushing native apps as the destination for mobile search — Android results began prompting installs for apps matching a query. Its own Webmaster Central team then published the counter-evidence from Google+: presenting visitors with an app install interstitial sent 69% of them away, and retention actually improved once the prompt came off.
That internal data point became the basis for external policy within weeks: Google announced it would demote pages whose app install ads cover significant content, then widened the rule into a general interstitial penalty taking effect January 10. The case study is the pivot where Google stopped just promoting app downloads and started pricing their cost into rankings.
First-order effects
- Publishers running app install interstitials on mobile pages now have quantified evidence — from Google itself — that the format trades most of their web audience for uncertain installs.
- Google+ kept the users the interstitial was losing, giving Google's search-quality team a retention argument to justify the September demotion announcement.
Second-order effects
- Advertisers still need app-promotion formats that don't block content, which is the gap December's Trial Run and Interactive Interstitial ad units fill — letting users sample an app for a minute instead of hitting an install wall.
- Google's parallel cleanup of accidental clicks on in-app interstitial and image ads, credited with conversion-rate improvements, signals the same pressure applied to its own ad inventory, not just publisher pages.
Third-order effects
- If the pattern holds, Google converts its own engagement measurements into de facto mobile web standards enforced through search rankings — the app-install penalty of 2015 generalizing into the broader January 10 interstitial demotion.
- Publishers are pushed toward web-first engagement models rather than funneling mobile traffic into native apps, weakening the assumption that the app install is the terminal goal of mobile acquisition.
The trend: Google is turning first-party UX data into search-ranking rules, progressively penalizing any mobile experience — app walls today, ad interstitials next — that stands between users and content.