creating a group identification for one or more user groups by a computer system, a user group comprising a plurality of users of an online system and a group size of the user group;

anonymizing an identity of a user requesting content by replacing the identity with the group identification associated with the user;

tracking a plurality of different types of user interactions with the content on the online system from a plurality of users, the plurality of user interactions comprising one or more of: clicking to see more content, clicking to like the content, responding to the content, clicking to subscribe to a content provider, or rating the content;

collecting the plurality of different types of user interactions with the group identification;

updating a group action count for a first group based on the plurality of user interactions, the group action count indicating a number of interactions with the piece of content by any of the plurality of users in the first group;

calculating an estimated number of unique engagements with the piece of content via the online system based on the group action count and the group size of the first group; and

providing the estimated number of unique engagements to the online system as the engagement feedback for the piece of content.