On March 31, the Media Rating Council (MRC) announced it was lifting its advisory on viewable impressions for display advertising, bringing the industry one step closer to transacting on viewability for the first time. The point at which publishers are asked to deliver highly viewable campaigns is rapidly approaching. If you haven’t started to develop a strategy to maximize the viewability of your ads, I’d wager that in the next three months, you will.

There are many tactics that can be applied to improve your ads’ view ability: ensuring fast ad loads; lazy-loading advertisements; and redesigning a website to feature always in-view units.

One issue has gotten surprisingly little discussion, though: Ads are much more viewable on pages that people actually want to read. Take a look at the following figure, which was computed across a sample of a billion ad impressions across the month of May 2014.

We see there’s a strong relationship between what fraction of ads are seen and how long a person spends reading the page: as Engaged Time increases from 15 seconds to one minute, viewability goes up by over half, from 37% to 57%. Visitors who read for more than 75 seconds see more than 60% of advertisements.

This isn’t too surprising. Of course, people who read pages more deeply see more of the ads on the page, but it’s still worth taking note. We’ve argued for years that articles with higher average Engaged Time should be promoted because they represent the articles your audience is most interested in, and—in the days where viewability is more critical than ever—promoting your most deeply read articles makes good business sense, too.

Want more? Download the Chartbeat Quarterly.