Market Definition in the Printed Media Industry: Theory and Practice

This paper first discusses how the market is delineated in some recent antitrust cases in the printed media industry. It evaluates the extent to which the main features of the industry are incorporated into the analysis and affect market definition. In addition we argue that an econometric analysis that does not incorporate these features can lead to biased estimates of elasticities. As demand substitution is a crucial element for defining market, bad estimates of elasticities could blur the boundaries of relevant markets. Second we propose a simple model that encompasses these features and in particular the two-sidedness of the market. Thirdly, we review some empirical papers that analyse the issue of demand estimation in printed media. Finally, we perform a statistical estimation on a dataset of magazines in order to provide a measure of the possible bias that could arise in the estimation of elasticities when one does not use a proper model.