This document discusses different methodologies for measuring media concentration. It explains that measures need to consider both economic power and diversity in information flow. While traditional measures look at financial data like revenue, newer audience-based measures examine influence over audiences. However, these still measure market power. The document will examine problems with both types of measures and how to define relevant markets geographically and in terms of products or services. It will argue that both financial and audience data should be used to assess economic power and diversity in media.