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