Interesting but since the writing of this article (2012) Google do offer Multi Armed Banned Content Experiments... https://support.google.com/analytics/answer/2

Interesting but since the writing of this article (2012) Google do offer Multi Armed Banned Content Experiments... https://support.google.com/analytics/answer/2844870?hl=en https://support.google.com/analytics/answer/2844870?hl=en