Determining a number of unique viewers of a content item

A system, comprising:

• a data processing apparatus;
• and
• a memory apparatus in data communication with the data processing apparatus and storing instructions executable by the data processing apparatus and that upon such execution cause the data processing apparatus to perform operations comprising:
• receiving an identifier specifying characteristics of a user associated with a device that was used to present a given content item;
• identifying, from a set of user categories, a user category for the received identifier based on the characteristics, each user category of the set of user categories including a respective number of pseudo-users;
• assigning the received identifier to a given pseudo-user in the identified user category based on a non-linear distribution of identifiers per actual user in the identified user category;
• determining a number of unique users, including the given pseudo-user, that have viewed the given content item based on a total number of pseudo-users that have been assigned an identifier corresponding to presentation of the given content item;
• and
• generating and providing data that causes a device to present the number of unique viewers.

A non-transitory computer-readable storage medium having machine instructions stored therein that when executed by one or more processors cause the one or more processors to perform operations comprising:

• receiving an identifier specifying characteristics of a user associated with a device that was used to present a given content item;
• identifying, from a set of user categories, a user category for the received identifier based on the characteristics, each user category of the set of user categories including a respective number of pseudo-users;
• assigning the received identifier to a given pseudo-user in the identified user category based on a non-linear distribution of identifiers per actual user in the identified user category;
• determining a number of unique users, including the given pseudo-user, that have viewed the given content item based on a total number of pseudo-users that have been assigned an identifier corresponding to presentation of the given content item;
• and
• generating and providing data that causes a device to present the number of unique viewers.