What is Unanticipated Event

This chapter focuses on the event study assumptions. We should carefully consider these at the start and mainly when writing up the study. While the author also addressed the assumptions in other chapters, it is helpful to identify several key assumptions early on to ensure that they are fully understood and built into the design. He discusses the primary assumption of stock market efficiency, unanticipated nature of events, independence, and how this is relevant. Examples are provided of some of the key points. Finally, he introduces several measures that can consider these assumptions and discuss how the study design can be adjusted if we violate the assumptions.