Recent study published by Google analyzes its ad display platforms and explores the factors which affect an advertisement's viewability (e.g., ad size and page positioning). The study reveals that approximately 56.1% of all the impressions served on the Google ad display platforms could never have been actually seen, as they were served outside of the browser window.
In addition, a recent report published by the Association of National Advertisers, which highlighted the risks associated with Bot fraud, which is estimated to reach up to $6.3 billion next year. This report reflects the growing threat of fraudulent traffic to the digital advertising industry.
These recent publications contain important insights with respect to advertisement viewability, which we encourage you to review.