We receive a lot of questions about reporting differences between Google Analytics and Google Paid Search, here are some of our thoughts regarding this:

1. Browser limitations: There are limitatiation in older browsers where the referring information isn’t passed correctly, this can lead to differences in the statistics.
1. Click Fraud - Yahoo & Google don’t count every click or visitor that comes through the system.  This leads to GA visitors and no reported clicks.
2. Counting Methods - Google Analytics sets a different cookie than counting a click-through.  If 5% of internet isn’t using cookies (or robots are following content ads) then GA will count the visitors higher than the clicks.  This could lead to multiple GA visitors and only one reported click.
4. Page Loads - If your page runs slow, a click is counted…but the JS script isn’t ran properly.  This will lead to one click and no visitor.
5. 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.

With all of these potential reporting differences, all your tracking mechanisms will tell you a different story.  Our advice is to use a 3rd party tool to act in combination with Google Adwords data….you can’t assume that Google Analytics and Google Adwords (even with Auto-Tagging turned on) will work with each other and report similar data.