Metrics 101: Viewability

As part of our larger efforts to help build an Attention Economy—in which success is measured not by clicks and pageviews but by time and audience attention earned—we’ve publicly released our Description of Methodology, which outlines the measurement process on which Chartbeat’s MRC accreditation is based.

Given that this document is a bit well, hefty, we figured we’d briefly explain a couple of our signature metrics here on the blog.

What is viewability?

A viewable impression is a metric of online advertising that indicates if a display ad is actually viewable when it’s served. More specifically, the IAB and MRC define a viewable impression as one that’s at least 50% visible for at least one second. To keep it simple, viewability is a metric that tracks if at least half of a display ad has the chance to be seen in the viewable portion of a browser window for at least one continuous second. Technically speaking, one second is measured as 10 consecutive 100 millisecond observations.

For the full scoop on viewability check out our 101 series:

  • What is Viewability?
  • What Does Viewability Mean for Publishers?
  • What Does Viewability Mean for Advertisers?
  • Viewability Metrics

    Chartbeat is accredited for the following viewability metrics:


    A count of the number of impressions that were deemed “viewable” under the MRC’s Viewable Impression Measurement Guidelines.

    Chartbeat Methodology: Every 100 milliseconds on in focus pages Chartbeat checks every ad tagged with Chartbeat’s “data-cb-ad-id” attribute to see if over 50% of the ad has entered the viewport (the viewable portion of your browser window). When the ad enters the viewport Chartbeat checks every 100 ms to ensure that it has remained on the screen and the window has stayed in focus. After ten consecutive successful checks (one continuous second), Chartbeat designates the impression as viewable.


    The number of impressions that are considered non-viewable, standard, or premium


    These represent served impressions where the viewable status is not met, but they can be “seen” by the viewable decisioning function.


    This is calculated as a percentage and represents (Viewable Impressions + Non-Viewable Impressions)/Total Served Impressions.


    This is calculated as a percentage and represents Viewable Impressions / (Viewable Impressions + Non-Viewable Impressions).

    Note: We are accredited for a few additional viewability metrics required by MRC’s Viewability Guidelines.

    What’s the industry saying about viewability?

    Well, they are saying a lot. While opinions certainly vary, it seems the common consensus is that the new viewability standard is, at the very least, a step in the right direction:

    “I don’t believe that viewability is a performance metric at all, but is rather just a huge step up from the old ‘served’ impression metric that we have used for years. However, a focus on increasing viewability will result in greater performance on the major engagement metrics like Universal Interaction Rate and Click Through that marketers value highly. It is this increased performance that will eventually lead to higher CPMs.”

    Jeff Burkett, Sr. Director Ad Innovation & Product Strategy at The Washington Post

    “The current viewability standard, while clearly nascent, serves an important purpose. It introduces a baseline criterion for and measure of accountability. At the end of the day, it is a means to a larger end: increased brand spend that better aligns with time spent online.”

    Neeraj Kochar, Tremor Video

    “Viewability is a positive development. The industry is at a major crossroads as we’re dealing with a growing amount of traffic being non-human, which has created a polluted ecosystem. The viewable impression is one step in the process to help solve this problem. It’s becoming the anchor that will allow for engagement and exposure metrics to be used to evaluate campaigns and prove for brands the value of the impressions being served.”

    Mark Howard, Chief Revenue Officer at Forbes

    “Unfortunately, it’s going to take a while before viewability becomes a valid currency and is established as a key metrics in determining impression value. However, I do think that there is an opportunity for publishers to take advantage of this debate to maintain and increase premium rates as more media becomes traded programmatically.”

    Peter Jones, The Guardian

    “Until now the ad impression was, essentially, a mechanical event — the creative file being loaded on the Web page. The viewability standard transforms an impression into an opportunity to see event: something of inherent value to a brand, just as in traditional media”

    Yaakov Kimelfeld, chief research officer at Millward Brown Digital

    Chartbeat has become the first analytics company accredited to measure attention metrics for both display advertising and content. The Media Rating Council has accredited 21 of the metrics featured in Chartbeat’s advertising platform including viewability and active exposure time.

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