Viewable impression

In the online advertising industry, a viewable impression is a measure of whether a given advert was actually seen by a human being, as opposed to being out of view or served as the result of automated activity.

The measurement of ads visibility was first introduced in 2008 by Alenty[2], and the first system to deliver reports based on a viewable impression metric for standard IAB (Interactive Advertising Bureau) Display ad units,[3] called RealVu, was developed by Rich Media Worldwide and accredited by the Media Rating Council on March 9, 2010.

[4] Other companies to offer viewable impressions include DMA-Institute [5] OnScroll,[6] C3 Metrics,[7] Comscore,[8] and AdYapper,[9] while MSNBC utilizes ServeView, a proprietary system[10] in use since 2010.

Viewable impressions were developed as an improvement of the online impression metrics measured by first ad servers developed in the mid-1990s, which analyze HTTP requests in a server log and cannot provide information on events fired by a viewer’s browser; thus, they cannot measure whether ad content was actually visible to a viewer.

With the advent of the Internet, through log file server collecting data it was believed that ad views could be tracked with unprecedented accuracy and “number of different prospects reached” was removed from the equation, and a new CPM equation was created for the internet:

Eventually it became apparent that a large number of ad impressions measured for CPM pricing actually never rendered in the visible area of a viewer’s browser screen.

Partially to avoid the limitations of server side impression methodology many models emerged that were based on direct response: The Viewable Impression approach enables online advertising effectiveness to be analyzed based on stopping power, branding ability and level of engagement – the three key elements that drive purchase consideration and, ultimately, sales.

The Correlator can collect additional non-private information from the viewer’s browser, including the viewer’s operating system, browser type and version and a list of other ads that were previously rendered on the page to prevent duplication of ads on the content page.

The Correlator continues to monitor the ad space for each individual ad on the web page and its relation to the browser window dimensions, scrolling position and web page focus, considering if the viewer has scrolled the ad space in or out of the visible area of the browser window, minimized, tabbed away, or opened another browser or application window bringing the web page monitored out of focus or portion of the browser window with the ad space outside of the monitor screen.

The Correlator code continues to monitor the web page focus and scrolling position, location of ad unit(s) and the visible area of the browser window, and communicates to the reporting server logging the “Time in View” for the ads being delivered on the webpage.