the PPC Book|Pay Per Click Blog | Long Tail Thoughts in a Short Tail World

I get this question often so I’m writing an answer that I can just point people to. Here are some possible reasons that your Google Analytics and Google Adwords reporting clicks have a major discrepancy:

• Google Analytics reports visits, Google Adwords reports clicks:

  These are 2 very different metrics. For example, a user clicks your adwords ad, visits your page, then goes back to their google search results page, doesn’t see anything else they like, and then clicks your ad again. Voila - 2 clicks, 1 visit (session).

• A user bookmarks your Adwords referral link:

  Again, same scenario, multiple clicks on the URL, but 1 visitor.

• Incomplete page load:

  Your site could be slow, or the Adwords visitor changes their mind, and before your analytics code renders, the user hits ‘back’ or ’stop’.

Google also addresses discrepancies between Adwords and other 3rd party tracking solutions:

We’ve found that most discrepancies between web logs or third-party tracking software and AdWords reports occur due to the fact that third-party tracking methods are unable to detect all the clicks that your ads receive. There are several reasons for this:

* Google Network statistics: Google displays ads on a growing network of search and content sites and products. Typically, web tracking software is not able to recognize clicks from Google Network sites as being affiliated with Google. These clicks are generally labeled only with the third-party site name. If your ads are currently, or have ever been, distributed to Google Network sites such as About.com, AOL, Netscape, etc., we recommend using referrer headers and tracking URLs to monitor where your website visits originate.

* Browser limitations: There are limitations to your third-party tracking software’s ability to track website visits with referrer headers. Most recent Internet browsers automatically pass along a referrer header when a user clicks your ad and is brought to your site. This referrer header indicates what site the user came from. For example, if a user sees your ad on a Google search result page, clicks it, and is brought to your site, the referrer header would most likely read ‘http://www.google.com/…’ However, some older versions of Internet Explorer and Netscape do not support this functionality and will not send this information. Also, some proxies and corporate firewalls strip out the referrer headers.

* JavaScript not enabled: If your third-party tracking software uses cookies to record referrer headers, ad clicks that occur in a browser without JavaScript enabled will not be tracked. Your AdWords account, on the other hand, will record clicks that occur in browsers with or without JavaScript enabled.

* Repeat visits: Users may click your ad several times in a relatively short period when, for instance, comparison shopping or conducting research. Your third-party tracking software may not count these repeat visits to your site. As long as the click patterns do not fit a profile of abuse or invalid activity, however, they will be counted in your AdWords account statistics.

* Shared IP address: Some Internet Service Providers (ISPs) assign the same IP address to multiple computers. Your AdWords account statistics will reflect multiple clicks that occur from the same IP address, while your third-party tracking software may not.

Google analytics will also differ from other 3rd party tracking solutions.

At the end of the day, all your tracking mechanisms will tell you a different story. My advice is to use a combination of relatively trustworthy solutions and have redundancies in place. Adwords tracking, Google analytics, and then something to act as an antidote to all that Google data - maybe awstats or a paid solution like indextools. Lastly, there are your trusty log files which can be tedious to review but relatively reliable.