Upcoming change to Google.com search referrals

you may start seeing a new referring URL format for visitors coming from Google search result pages. Up to now, the usual referrer for clicks on search results for the term "flowers", for example, would be something like this:
http://www.google.com/search?hl=en&q=flowers&btnG=Google+Search Now you will start seeing some referrer strings that look like this:
http://www.google.com/url?sa=t&source=web&ct=res&cd=7&url=http%3A%2F%2Fwww.example.com%2Fmypage.htm&ei=0SjdSa-1N5O8M_qW8dQN&rct=j&q=flowers&usg=AFQjCNHJXSUh7Vw7oubPaO3tZOzz-F-u_w&sig2=X8uCFh6IoPtnwmvGMULQfw
The key difference between these two urls is that instead of "/search?" the URL contains a "/url?". If you run your own analyses, be sure that you do not depend on the "/search?" portion of the URL to determine if a visit started with an organic search click. Google Analytics does not depend on the "/search?" string in the referrer, so users of Google Analytics will not notice a difference in their reports, but other analytics packages may need to adapt to this change in our referrer string to maintain accurate reports.

AdWords A/B testing

A/B test shows a statistically significant difference is:

1. Define N as "the number of trials."
   For Hammy this is 8+4 = 12.
   For the AdWords example this is 32+19 = 51.
   
2. Define D as "half the difference between the 'winner' and the 'loser'."
   For Hammy this is (8-4) ÷ 2 = 2.
   For AdWords this is (32-19) ÷ 2 = 6.5.
   
3. The test result is statistically significant if D2 is bigger than N.
   For Hammy, D2 is 4, which is not bigger than 12, so it is not significant.
   For AdWords, D2 is 42.25, which is not bigger than 51, so it is not significant.