The cool thing about Google Adwords versus other advertising platforms is the control you get in the settings section.
For an effective split test you need a decent sample size before you optimise. Unfortunately if you miss this setting and have “optimise for clicks” then adwords may begin showing one ad over another before it is justified. This means you are working with faulty data.
For the novice this is probably ok as the concept of testing is not applied, so it is done for them. If however you really want to know if one if piece of ad copy is more effective than another, my recommendation is to rotate evenly, label the ads and make sure you have a decent amount of data before forming your conclusion and testing again.
About the author
Thomas Green is a Certified Adwords Professional and specialises in direct response marketing. He has over 6 years PPC experience and has a straight forward approach to what works and what doesn’t!