google adwords: ad rotation configuration and optimizing ad impressions

In Google Adwords, you can have multiple ad groups with in a campaign. Each of these ad groups can in turn have multiple ads. When a search query (or a page in display network) matches one of the keywords in the ad group, an ad from the ad group is shown to the user. That is probably a rough and quick explanation of how Ad groups in Google Adwords work.

If you have been using Google Adwords for any length of time, you might have noticed that one of the ad have a dis-proportionally high number of impressions compared to the other ads with in the same ad group. You will also notice that it is usually the ad with the highest Click-thru Rate (or CTR) that has the highest impression.

It is really not a surprise that this happens, as Google tends to show the “best” performing ads much more often than the other. Each ad with in the ad group basically “competes” against one another to see which of the ads perform better. My guess is that it follows something like a multi-armed bandit approach in A/B testing to predict a better performing ad.

However, I have also noticed that the ads tend to get a winner much quickly than to my liking and the other ads usually languish with out getting a whole lot of impressions. Most times this works out fine as there is no reason to show the ads that are not doing well and anyway you should replace those with newer ads.

But when I do create new ads, it does not seem to get the required (or my target impression count) impressions quick enough to compare it to the previous ads. We will see how you can configure how the ads are shown to user. This will let you see how the ads perform compared to each other all the while getting to a minimum number of impression of your liking much faster.

The configuration in Adwords that gives you control over how the ads are shown is with in the Ad Rotation settings in the Settings tab in the Campaign.

  1. Go to the desired campaign by clicking on the Campaign in the left hand side menu
  2. Click on the Settings Tab
  3. Under Advanced Settings, click on Ad Delivery
  4. Click edit in the Ad Rotation option
  5. Select an option that suits you
Ad rotation settings

There are four different options that you can choose from. Each of the options should provide you with a description that explains how the rotation works. You can always change it later.

Optimize for Clicks: This option is good if you want to drive as much as traffic you can to the page. The CTR and number of clicks are the metrics that are optimized in this case. This is the default option if you do not explicitly change it when creating the campaign.
Optimize for Conversions: This works best if you have a definite goal or Conversion defined for the campaign. If you are already tracking conversions for your pages then choose this option for maximum return on investment.
Rotate Evenly for 90 days: This option is geared towards eliminating the issue that I detailed earlier in the post. This will show the ads much more evenly for up to 90 days and then will start to optimizing the ads for clicks based on the accumulated metrics. If you already have the conversion optimizer enabled, then it will optimize for conversion after 90 days.
Rotate Evenly Indefinitely: This option is probably the least ideal and you should mostly stay away from it unless you are monitoring and optimizing the ads on a regular basis.

Which of the above option you want to choose will depend very much on what your goals or requirements are for the specific campaign. It is really difficult to come up with a configuration that fits all scenarios. If you really have to, then I will recommend that you leave it at default, which is the Optimize for Clicks option.

Ideally, you should do conversion tracking and then choose the Optimize for Conversion option. This is probably the best option for most users. Even if you do not have an E-Commerce site that generates revenue or something that is a straight-forward conversion metric, you can still optimize for page views or session duration.

However, if you do monitor your ads regularly and optimize them yourself, then Rotate Evenly for 90 days might be the best option for you. This allows you to accrue impressions evenly much faster and then make your own decision on which ad is performing better. You should ideally be monitoring the campaign every week or so and creating/optimizing ads for the ones that are not performing well.

You could potentially be losing some “conversions” because you want to generate impressions much more evenly and much faster. I said potentially because there is no real way to know for sure. There is a chance that you might be performing better than Google’s optimization if you are optimizing it regularly. You can always compare your performance to previous periods to get an idea.

Another quick and easy way for you to accumulate ad impressions for a particular ad is to pause the (other) ad that is currently accruing the most impressions. This is probably not an apples to apples comparison when it comes to a strict statistical analysis, but it works in most cases. I leave the best performing ad paused for a while till the other ad (newly created ad) generates enough impressions (say about 1000) so that i can compare between the two and optimize.