"Mike, the reason publishers aren't dealing with viewability is that the Media Ratings Council has an advisory urging people not to use viewability as a metric this year. Why? Because there is no common standard for viewability. At ZEDO and ZINC, we use comScore measurements, but there are also other standards. And besides, viewability has no bearing on engagement (and thus results). Our Zinc division is looking for engagement. An ad is now viewable if 50% of its pixels are in view for at least one second. Can YOU respond to an ad that's viewable for that short a time? Or that's only half viewable? The idea of viewability is good, of course, but we're quite a way from the reality." - Francine Hardaway