As most of us who advertise on Google’s “display network” know, there are a few ways to go about it. Some of the more notable differences include:

Ability to target automatic placements, either via audiences (a newer feature), or via keywords


Ability to target managed placements (websites or web pages you choose) with or without keywords or audiences

Ability to advertise with text ads


Ability to advertise with image ads

The way in which you choose to combine these options can have a drastic effect on the success of your display PPC campaigns, and as we’ve discussed previously, you have to continually test and modify your methods to properly leverage the power of this rodeo of a distribution channel.

As you may have noticed, Google recently started referring to what was previously the “content network” as the “display network”. I think that gives an indication of the direction Google would like to, or intends, to take this distribution network in, and so today I’d like to explore some of the differences we’ve seen in ad groups targeting image ad delivery only vs. similar ad groups targeting text ad delivery.

Generally, as per a recommendation from our Google reps, we have not been targeting managed placements without keywords. Most of our campaigns initially are set up to target automatic placements with a small, specific keyword list. Based on further recommendations from Google, this year we created ad groups running only image ads based on historically successful ad groups running only text ads.

One thing to keep in mind is that the way in which duplicate ad groups and keywords on the display network compete with one another is much more nebulous than the way in which duplicates on search work. At this point all I can say is that in our experience, our image ad groups tend to have higher traffic (both impressions and clicks) than their corresponding text counterparts, but I don’t have the capability to tell you whether that’s because the image ad groups are getting traffic that their duplicate text ad groups would receive if the image ads were not available, or if the image ad groups just have greater distribution capacity. I suspect that it works in a way similar to search and that if any of my display ad groups themes match to the Google-determined theme of a website, Google chooses which ad group to show the ad from and is preferentially choosing the image ads, but it’s just a theory (though one based on Google’s info about text and image ads serving within the same ad group). If any of you have had experience with text display ad group traffic decreases after adding duplicated ad groups with only image ads, I’d love to hear about it.

As a trend, we have also seen better cost per lead performance for image ad groups than their corresponding text ad groups. Why is this? Let’s check out some comparisons from two directly comparable ad group sets. Each set contains two ad groups. One ad group contains only image ads, one contains only text ads. Both have the same keywords and the same display bids, are only targeting the display network, and are running only automatic placements.

Is the relevancy of sites on which ads appear is higher for image ad groups?

Not really. Though you always have to be aware of the possibility of fraudulent clicks on the display network, as it’s still kind of wild-westy, on average the type of sites and pages we are being matched to for image ad groups are very similar to the types we are matched to for the same keywords in text ad groups according to our placement reports.

Are click-through rates higher for image ad groups?

Not consistently.  Though this can vary widely depending on the quality of your text ads vs. image ads, our text ad messaging is similar to our image ad messaging, and in most cases we haven’t seen huge differences in click-through rates, probably because the sites they’re showing on are similar. In the two sets above, you can see examples of both situations. The differences are not enormous, but in one set the text ads have higher CTR and in one the image do, and this is reflective of the variation we’ve seen across our ad groups.

Are conversion rates higher for image ad groups?

Not consistently. We’re using the same landing page for both our image ads and our text ads, and as mentioned above, the image ads have similar messaging as the text ads. Once again this has varied across ad groups, with text vs. image ad conversion rates being higher on an ad group by ad group basis, but no consistent pattern of higher image ad conversion rate has been established.

Is average cost per click lower for image ad groups?

Usually! Average cost per click is lower and average position higher for the lower cost in our image ad groups. I don’t know why, as Google says that image vs. text pricing should be consistent, except to say that Google may consider image ads to have a higher quality index than text ads and therefore be discounting their CPC in the same way the higher Quality Score keywords have a lower CPC than lower Quality Score. Though many other performance metrics varied across our image and text ad groups, cost per click (when bids were identical for each ad group) was consistently lower for image ad groups. And of course, lower cost per click with similar conversion rates leads us to lower cost per lead.

Given these initial observations after running concurrent ad groups for several months, for newly developed display campaigns or when we’re attempting to lower display cost per lead, I’d prefer to start with image ad groups in conjunction with text ad groups. Though we’ve seen much success from running text-only campaigns on the display network and continue to have many accounts with successful text-only display ad groups, I think there’s growing evidence that well-designed (and well-tested, as always with all ads) image ads have the potential to be even more successful, whether that’s because Google prefers them or because they naturally are more user-friendly. On the other hand, there are sites that won’t show image ads but may be successful for text ad groups, so completely eliminating text ad groups probably isn’t the best idea. But: if you haven’t considered adding image ads into your display marketing mix, I’d seriously reconsider at this point in the Google game.