Chapter 4 describes how analytical journalists acquire knowledge about what the public knows about the causes of current phenomena, which is a prerequisite for improving the public knowledge base. The chapter describes framing theory to understand the impact of journalism on audience and the concept of issue frame as journalistic portraits of reality that includes causes creating a phenomenon. The chapter presents the second phase of analytical journalism, which consists of an inductive strategy and guidelines for three methods of mapping media content: (1) A representative collection of media examples in the public knowledge base. (2) A content analysis to identify issue frames in media examples. (3) An issue frame table as a tool to categorise the existing causal explanations in a specific public knowledge base, which gives an impression of what might not be so familiar to an audience.