Relative CTR: While clickthrough rate (CTR) indicates how often users click on ads it can't tell you how ads perform compared to other ads on the same page - enter "relative CTR" which shows advertisers how ads perform relative to those ads being displayed on the same places on the Google Display network. For example, if your display ads have a CTR of 0.04%, while other ads in the same places on the GDN have a CTR of 0.02%, your Relative CTR is (0.04)/(0.02) = 2x. Relative CTR will be a solid indicator to advertisers they they are outperforming or underperforming other advertisers and that display ads are resonating.
Impression Share: Google also released the Impression Share (IS) feature which represents the percentage of times that ads were shown out of the total available impressions on the Google Display network. For example, advertisers may notice they are losing 25% of impression share due to budget restrictions and must increase this campaign's daily budget to get more impressions. Or that they are losing 35% of impression share due to Ad Rank and may need to raise bids or improve creatives.
Two other notable features were released for the GDN this week including the Unseen Impression Filter which ensures that advertisers are not charge for impressions that have a low probability of viewing, and the Content Ads Diagnostic Tool (CADT) which indicates why ads aren't showing.