Measuring a networked audience is described. Initially, a first set of network usage data is determined based on a first set of signaling information obtained from a first subset of the client systems as a result of the first subset accessing common resources. In addition, a second set of network usage data is determined based on a second set of information obtained from a second subset of the client systems as a result of an application installed thereon monitoring accessing of the common resources. Usage is measured based on the first set of network usage data by determining an initial count of unique visitors that accessed the common resources by determining a count related to signaling of the first set of signaling information. Adjustment factors are determined based on the second set of network usage data. Finally, audience reports are generated by adjusting the measured usage using the one or more adjustment factors.