1. A computer-implemented method for developing user profiles within a profile corpus, the method comprising: determining topics associated with digital content items; organizing user profiles of users into a plurality of demographic groups based on demographics of the users; retrieving access data indicating interactions of users in a demographic group from one of the plurality of demographic groups with a plurality of the digital content items; identifying the topics associated with the plurality of digital content items interacted with by the users from the demographic group as candidate topics to include in user profiles of the users in the demographic group based on the access data; for each candidate topic, identifying, topics included in the user profiles of the users in the demographic group that co-occur in the user profiles with that candidate topic; selecting, by a computer, a candidate topic from the candidate topics to include in a target user profile of a target user from the demographic group based on co-occurrence of the candidate topic with one or more topics included in the target user profile that were identified from the user profiles of the users in the demographic group as co-occurring with the candidate topic; and adding the selected candidate topic to the target user profile of the target user from the demographic group.
1. A computer-implemented method for developing user profiles within a profile corpus, the method comprising: determining topics associated with digital content items; organizing user profiles of users into a plurality of demographic groups based on demographics of the users; retrieving access data indicating interactions of users in a demographic group from one of the plurality of demographic groups with a plurality of the digital content items; identifying the topics associated with the plurality of digital content items interacted with by the users from the demographic group as candidate topics to include in user profiles of the users in the demographic group based on the access data; for each candidate topic, identifying, topics included in the user profiles of the users in the demographic group that co-occur in the user profiles with that candidate topic; selecting, by a computer, a candidate topic from the candidate topics to include in a target user profile of a target user from the demographic group based on co-occurrence of the candidate topic with one or more topics included in the target user profile that were identified from the user profiles of the users in the demographic group as co-occurring with the candidate topic; and adding the selected candidate topic to the target user profile of the target user from the demographic group. 2. The computer-implemented method of claim 1 , wherein adding the selected candidate topic comprises: adding the selected candidate topic to the target user profile of the target user from the demographic group responsive to the target user profile not including the selected candidate topic.