Abstract: In one embodiment, a method includes using a processing system to access a first set and a second set of user accounts in an online social network. The first set and second set of user accounts are predetermined as belonging to a first category and a second category, respectively. From each user account in the first and second set, the system may extract feature values corresponding to a set of predetermined feature types, which includes at least a feature type relating to profile information and at least a feature type relating to posting information. The system may then train a machine-learning model using the extracted feature values. The trained machine-learning model may be configured to predict whether a third user account in the online social network belongs to the first category or the second category, based feature values corresponding to the feature types extracted from the third user account.