George Williams, Keith Brown and Peter Alexander.
Media Bureau Staff Research Paper 2002-9 (Sept 2002) develops a unique measure of product diversity, and applies it to R&R playlists to examine changes in diversity following the 1996 Telecommunications Act. This study represents the first attempt to measure diversity in radio markets using actual songs.
The authors find modest changes in diversity, with a slight decrease in the diversity of songs within the same R&R format across local markets. They also find a slight increase in the diversity of songs within the same R&R format within each local market.