I think you may be talking about the 2 ad serving choices Google offers at the campaign level. If you have multiple ads in an ad group, they will rotate equally or Google will serve the one that performs better more often.
If you're testing multiple adverts (which you should be), you should rotate them equally, or your results will potentially be wrong.
CustardMite, if you are doing A/B testing for your copy turn off the optimizer. You want them to rotate evenly so you know which ad is better. Cheers, ZigZag
Optimized ads comes into play when you create multiple ad variations. Optimized ads means those ads would be shown more often which has been "performing better". Though I am not sure what google exactly mean by "better performing". I think it refers to higher CTR of ads. On the other hand it would show all ads equally if you select to rotate ads.
I think that "performing better" in Googles mind is a higher CTR pecentage. The real question is when does Google decide that one ad is much better than the other? I don't think I have a single campaign that rotates evenly, but then again I am a control freak when it comes to Adwords...
Question, How long does it take before you notice that changing from rotational to optimized? I changed this option about 3 days ago on one of my campaigns and today it still shows them having an even spead between 4 ad's.
I suppose it depends on how long it takes Google to determine which advert is 'better'. Why would you want to use optimised anyway? Google will make decisions on the clickthrough rate, not the conversion rate or cost per conversion, which are far more important. Though none of these is really what you're really interested in. They are all only indicators of how profitable an advert is, and they can all be misleading, viewed in isolation...
Thanks for the Info. I agree with you. I was just split-testing some ads and wanted to see if changing to optimised would make it any better but sadly it s taking it's sweet time or it made no difference.