Google really doesn’t trust the average Adwords user when it comes to split testing their ads.
How do I know?
In Adwords campaign settings, Google gives users two options for ad rotation:
I recommend that as an advertiser you shouldn’t listen to Google’s recommendation to optimize your ads. Letting Google pick your best ads will kill your split tests before you collect enough data to truly declare a mathematical winner.
Despite this, Google has always set the default for this setting at “Optimize,” even going so far as to recommend it for new advertisers.
Recently, as of August ‘09 Google updated their Adwords web interface to make it even harder to change this ad rotation option.
In fact, if you’re setting up your new campaign settings before you write any ads, as I’m sure many do, it’s literally not an option for you.
Here’s a screenshot of the ad rotation setting for new, ad-less campaigns:

So, if showing your ads evenly is the best way to run split tests to get fast results, why doesn’t Google set this as the default?
I speculate about this and write about two other settings you should go against Google’s recommendation on for every new Adwords campaign you create in my post, “3 Adwords Settings You Must Change to Avoid Campaign Suicide.”
I recommend that as a smart advertiser you should set up your ads (or just create a test ad) and change this ad rotation setting to “Standard,” giving all of your ads an even shot at becoming winners for your campaign.
Related posts:
Unlike any other business Google seems to go out of it’s way to ignore the people who pay its bills.
So far it’s been very good at exerting its power in different ways, but I think the day will come when Google will be the one getting slapped.
In fact I think it will eventually spread into so many markets, it will be the target of anti-trust action.