Ad server reports clicks but Web Analytics tool does not show traffic

Often times the ad server would report that the online advertising (Display and Search) is generating clicks but the site analytics tool like Webtrends, Omniture etc does not report traffic. One of the first things to check is if the consumers who are clicking on the ads are actually loading the landing page.

One of the ways to check that is by putting an ad server tag on the landing page and thus be able to track the click to landing page load rate showing the abandonment rate from click to page load. The number of landing page load should match very close to the web analytics tool numbers.

There could be still some discrepancy of about 10-15% due to:

- Webanalytics tool click-throughs are de-duped

- The adserver code could be at a slightly different place than the web analytics tag and will have differing execution times

- Javascript disabled users would count the ad server tag but most of the web analytics tags need Javascript enabled browsers

How does Digital Ad Serving Work?

How do all these banner ads get placed and how does this work? First let's talk about what is an Ad Server, as per ZDNet's dictionary, an Ad server is defined as a "Web-based server that delivers banner ads and popup ads to the requesting Web pages. For companies that sell their own ads, the adserver may be an inhouse or co-located machine at an ISP, or it may be owned by an Internet advertising company".

The Ad publisher or the site where the ad will be placed contacts the Ad server to get the creative every time the page loads. Based on how the inventory for that particular placement has been sold, the ad server provides the particular creative to be published. This communication happens real time and sometimes slows down the page load. This is the main reason by sites like MSN, AOL do not want to use third party ad serving on their key homepage placements as they have over 100MM impressions in a day and if the page load is slow, they might lose consumers coming to their site.

The reporting part of the Ad server then captures the number of impressions, clicks, post-click activities, post-impression activities and all the other standard metrics based on how and what things have been tagged.

Cookie Window, what is it, what is the optimal length?

A lot of times we come across the term – “Cookie Window” or media folks talking – “There is a 30 day cookie window on this campaign”. What does that mean? This means that consumers who clicked on a digital banner or a search result have 30 days to return to your site and take the action that is being tracked. If the consumer had clicked on the ad, it will be shown in post-click activity and if the consumer had not clicked on the ad, it will be tracked as post-impression activity.
The optimal length of the window should be chosen based on each individual campaign or business, it should be tested and then the correct decision should be made. Typically, a click to conversion or action lag report is available from the ad server like DART or Atlas which shows the time tag between the click and the conversion or action. This is very important for DR (direct response) businesses which are trying to either sell something on their website or have a clearly defined action as then they can adjust the cookie window based on that.


As shown from the chart above, this is a clear increase in the number of actions up to day 10 and then there is a decline through day 15 and after that there are minimal actions. Thus, looking at this chart a cookie window of 15 is the optimal length for this business.