Mobile Display Ad Viewability Metrics By Ad Size, Q3 2014 [TABLE]
Screenwide display ads on mobile were tops for viewability, with in-view rate for 320×50 placements coming in at 64.6%—nearly 18 percentage points above average. Next came vertical 300×600 ads, which had an average in-view rate of 51.4%; 728×90 leaderboards were close behind, though, at 51.1%. Just like with desktop, vertical mobile display ads had the longest in-view time: 18.6 seconds for 160×600 placements and 18.0 for 300×600 ads. Read the rest at eMarketer.