This paper: (i) reports an empirical regularity in the market shares of brands; (ii) presents a theoretical framework for understanding the observed regularity; (iii) adduces additional empirical consequences of the framework, which are some counterintuitive relationships among market shares of brands across different product categories; and (iv) presents empirical evidence for these consequences, thus providing additional support for the theoretical framework. Our cross-sectional data on market shares consists of 1171 brands in 91 product categories of foods and sporting goods sold in the US. The key empirical regularity is that, in each category, the decrease in the market share between two successively ranked brands becomes smaller as one progresses from higher-ranked to lower-ranked brands. The power law represents these patterns well, in an absolute sense, and better than an alternative model, namely, the exponential form, which has been studied in the literature but without having been compared to any alternative. The latter form predicts that the ratio of the market shares of any two successively ranked brands is a constant. We present some potential implications of our findings. We also offer an interpretation of the previously known square-root relationship between market share and the order of entry of firms into an industry. The theoretical framework that we present for understanding the patterns reported here shares its foundation with that of the familiar Dirichlet-multinomial paradigm of brand purchases. This framework has some intuitive interpretations; it accommodates multiple product categories; and it allows for the entry and exit of brands over time.
Download Info
To download:
If you experience problems downloading a file, check if you have the
proper application to
view it first. Information about this may be contained
in the File-Format links below. In case of further problems read
the IDEAS help
page. Note that these files are not on the IDEAS
site. Please be patient as the files may be large.
Publisher Info
Paper provided by Harris School of Public Policy Studies, University of Chicago in its series Working Papers with number
0604.
References listed on IDEAS Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.: