Why is the CTR low on my Site Retargeting campaign?

This article discusses why you may be seeing a lower CTR for your Site Retargeting campaign.

For site retargeting-only campagins, the primary key performance indicator is full delivery of ordered impressions.  Site retargeting campaigns serve ads to users who have previously visited the client's website with the hope that the users visiting the client's site will convert in the future because they have shown interest in the past. 

We do recommend swapping creatives every month to six weeks in order to keep the CTR of any campaign high. If we have been running the same creatives for a long period of time, it's possible users have grown used to seeing the same ads and are not engaging as much. We recommend sending new creatives with a strong call to action to improve the overall CTR.