Enhanced Matching

The Enhanced Matching feature for the Quantcast tag may help you improve the quality and accuracy of the audiences you create in our platform. To take advantage of Enhanced Matching, you will send us hashed user information (ideally an email address) through the tag on your website. To protect user privacy, hash all emails passed to Quantcast. Any unhashed emails will be dropped.

New & Existing Tags

To set up Enhanced Matching when adding the Quantcast tag for the first time, enable the feature when you get your tag from within your Quantcast account. 

This will add an extra line of code to your tag. 
If you already have a Quantcast tag on your website, you can add the following line of code to the tag(s):

var qcdata = {qacct: "p-1234567890123", uid: "__INSERT_EMAIL_HERE__"};

See this example:

Google Tag Manager

If you use Google Tag Manager, add a variable containing the currently logged in user’s email address in the User ID parameter in the Quantcast tag template.

For more information on using variables in Google Tag Manager, go here.