"Key-values" are core DFP features that allow you to set information about the user or his context to each page view and target campaign. Examples of key values:
Gender
UserType (guest, authorized)
Page type (category index, article, feature etc)
Content category ([sports, football], [politics, USA, Trump] etc)
The main difference of key-values towards 1st party Audience segments is that they are accessible inside the creative using %%PATTERN:TARGETINGMAP%% macro, so they can be sent to AdForm SSP, Improve Digital or other ad-servers.
It is easy to target campaigns. However, you need to have an overview over how many impressions can be delivered in a target group. For particular key-values, an inventory check will give you some insights, although it does not show how many users are in the target group. To see this, go to the Audience Explorer for 1st Audience Sync.
You can build a report that shows how many impressions AudienceProject targeting data has by following this step-by-step guide:
Go to the "Reports"-tab
Create a new report
Choose the historical report type
Choose proper data range
In filter, choose Key-values containing ap_ criterion
In dimensions, choose Key-values
In metrics, choose Impressions
Press Run report
As a result, you will obtain the following type of table
In order to read this report, you will need to have a segment translation from your AudienceProject account manager.
In case you want to re-send key-values to other Ad-servers, you might be interested in how many impressions are within the target group. This can be done by creating a report with a filter on Advertiser:
