1. A system comprising: one or more processing devices; and one or more storage devices storing instructions that, when executed by the one or more processing devices, cause the one or more processing devices to perform the following operations: access a first data set associated with a first group of users, the first data set including demographic data, online behavior data, and additional user data associated with the users in the first group; access a second data set associated with a second group of users, the second data set including demographic data and online behavior data but not additional user data associated with the users in the second group; determine one or more sets of matched users based on the demographic data and online behavior data included in the first data set and the demographic data and online behavior data included in the second data set, wherein each set includes a user from the first group matched with a user from the second group; generate, based on the one or more sets of matched users, an augmented second data set that includes additional user data associated with the users in the second group; and generate one or more reports based on the augmented second data set.