Discrepancies between Pulse and third-party data

Click tracking with Google Analytics

Google Analytics (GA) uses javascript to call a property named referrer, which normally contains the URL of the page that the user came from. Issues can occur with the referrer if the last click came from within a browser plugin (like Flash), as it does not contain anything at all. For example, instead of referrer="http://www.mysite.com", it would be referrer=null. Because of this, sites that use GA to track where users came from have a high discrepancy. The solution is to use a redirect tracker instead, meaning use a link like http://tracker.com?site=one&redirect=http://www.one.com that first tracks the click-through and then forwards the user to the real URL.

No cache busters

If you use URLs that always look exactly the same, most browsers cache the response, and the next time the link is called, the browser does not bother to call it as they have it stored in their memory already. This leads to discrepancies, especially with third-party impression trackers.

The solution for this is to always add cache busters, like ${random} or ${timestamp}, to the impression URLs. For example, http://tracker.com?track=campaign1 becomes http://tracker.com?track=campaign1&rnd=${random}. For more information, see Cache busters.

Sequential latency

The initial request usually first comes to the third-party server and then the third-party (for example, Adform) pixel is fired. There can be a difference of 0.2 to 0.8 seconds, depending on the viewer’s connectivity and bandwidth to both Adform and the third-party system. During this period, discrepancies appear as some connections may be cut off either due to the viewer’s actions (such as closed browser’s window, interrupted page load by loading other web pages, or clicking back/forward), or lost internet connection.

Slow page loading

Pages might load slower than usual due to internet related problems, or any connection problems with the item on the page, for example page elements from external sources, such as images or scripts.

Viewer behavior

Depending on the website, a viewer might be able to navigate from the initial page to the page they are interested in without waiting for the whole content to be loaded. Closed browser tabs or windows also fall under the reason for discrepancies.

Differences in counting methodologies

Third-party ad servers, such as Adform, count an impression as soon as a request to the ad server is made. Third-party ad servers usually count a tag load before providing the content and before a request to Adform is made. Other than that, some requests depending on user agent string or IP might be classified as robotic and withdrawn from statistics.

Ad blockers

Various ad blockers may block different ad servers. As a result, some third-party servers may not be blocked while Adform is blocked. In such cases, Adform never has a chance to count an impression.