On the heels of Google’s sunsetting of ad rotation in AdWords  I had some additional questions about how, exactly, the “new ad rotation” would work, so I connected with our Google AdWords rep to get answers to my questions.
Here’s what Google had to say about the change:
AdWords currently offers three ad rotation settings: optimize for clicks, optimize for conversions, and rotate evenly. Using the “rotate” setting for ad rotation is helpful for testing new creatives, but when run indefinitely can inhibit advertiser performance and deliver less relevant ads to our users.
Starting next week, the “rotate” setting for ad rotation will change. Instead of rotating creatives for an indefinite period of time, this setting will only rotate for a period of 30 days. After that, the setting will then optimize to show the ads expected to generate the most clicks. Every time a creative is enabled or edited, the ads in that ad group will rotate more evenly for a new period of 30 days.
My questions were mainly around how this 30-day period of time would actually be implemented, and specifically I wanted to better understand how the setting worked so that I could understand how to create good split tests moving forward. I thought other advertisers might find the answers to my questions useful, so here’s the back-and-forth from that email exchange:
My Initial Email
I saw the way ad text rotation is being handled is changing and had a couple quick questions:
- If I set an ad campaign live and then pause it after say 10 days, then unpause the ad a month later, does it still have 20 days left of "ad campaign" or will it switch right to optimize for CTR?
- If I run an ad on rotate for 30 days then pause it and create an identical ad, I'm assuming that doesn't impact how the other ads in the ad group are treated? In other words, will the ads rotate for 30 days from when the ads within a given ad group are created, or will they run for 30 days from when the campaign is created/set live? And how do new ads being incorporated into an ad group with this setting impact how long the ads run on rotate, if at all?
The Response from an AdWords Representative
- It allocates for 30 days of run time, which means it still requires the remaining 20 days.
- The ads will rotate for 30 days for when they run for 30 days (similar to the above question). New ads are still incorporated into rotation (this hasn't changed), but it will prioritize certain ads based on CTR.
A follow-up from me
So just to make sure I'm understanding correctly here:
If I have ads A, B and C and they run for 30 days, then I pause A and create ad D, the ads may run on rotate for 30 days but if B or C has an exceptional CTR it may actually get shown more frequently. And the same would be true if there were only two ads (i.e. if ads A and B were running for 30 days, I paused A and created a single new ad, it may not rotate evenly against B for a full 30 days if B had an exceptional CTR).
Is that correct?
The final response from Google
Yep, that's correct. The definition for "exceptional CTR" is also not a set amount, but more along the lines of being significantly higher than whatever CTR exists for other ads.
So in setting up ad tests, it’s important to note that Google is effectively “reserving the right” to promote a winner based on exceptional click-through rate (in other words: creating copies of an existing ad and introducing a new ad to the auction isn’t a workaround for extending the length of a test), and if you’re setting up an ad and then you pause it, it requires the full 30 days active to move from rotate to optimize for CTR.
About the Author
Tom Demers  is co-founder and managing partner at Measured SEM , a boutique search marketing agency offering search consulting services  including pay-per-click account management, comprehensive SEO site audits , content marketing strategies and services , and a variety of link building  packages such as guest posts  and blogging strategy .