«(...) the impact of radio play on sales of sound recordings using a sample of American cities. The results indicate that radio play does not have the positive impact on record sales normally attributed to it and instead appears to have an economically important negative impact, implying that overall radio listening is more of a substitute for the purchase of sound recordings than it is a complement.»

Liebowitz, Stan J., "Don't Play it Again Sam: Radio Play, Record Sales, and Property Rights" (January 5, 2007). Available at SSRN: http://ssrn.com/abstract=956527