1. A computer-implemented method, comprising: receiving, by an analytics system, a first segment definition and a second segment definition, each associated with an account identifier identifying a tracking account for a network property and that is maintained by the analytics system, wherein: the first segment definition defines a first segment of visitors to a network property and, for each visitor in the first segment, includes a visitor identifier identifying a device used by a visitor to visit the network property and which is issued by the analytics system; and the second segment definition defines a second segment of visitors to a network property that is different from the first segment of visitors and, for each visitor in the second segment, includes a visitor identifier identifying a device used by a visitor and which is issued by the analytics system; determining, by the analytics system, whether the first segment and second segment definitions present a personal information exposure risk for one or more of the visitors; only in response to determining that the segment definitions do not present a personal information exposure risk for one or more of the visitors: accessing, by the analytics system, tracking data communications for the network property associated with the account identifier, each tracking data communication including a visitor identifier and one or more event statistics describing one or more events related to a visitor interaction of a visitor with the network property; determining, by the analytics system, one or more segment signals from the tracking data communications that include the visitor identifiers of the first and second segments, each of the or more segment signals positively correlated with only one of the first segment or the second segment; and generating, by the analytics system, reporting data describing the segment signals and the correlation of the segment signals with the respective first and second segments.