Abstract: To assess the effectiveness of advertising campaigns and channels, a portable user appliance is provided to each of a plurality of panel members. Each device includes a scanning module for scanning and storing a UPC code for each product purchased by a corresponding panel member, a processor, a memory, a user-interface, and a communication interface operative to transfer information stored in memory to a central facility. Each device further includes a microphone and is operative to monitor an audio portion of at least one of a radio broadcast and a television broadcast. UPC codes and information corresponding to purchases made by each respective panel member are received from the portable user appliances, as are transmissions from which the identities of advertisements included in monitored audio portions can be determined.