The present invention provides techniques for use in audience-related measurements, including hybrid techniques which include use of panel-based audience-related measurement information and census-based audience-related measurement information. Techniques are provided in which panel-based audience-related measurement information is obtained from multiple providing entities, and census-based audience-related measurement information is obtained one or more providing entities. The obtained information is stored in a database. The stored information may be provided to the information-providing entities, and may be used in calibrating or improving the accuracy of audience-related measurements.