Methodologies
The general event study methodology is explained in, for example, MacKinlay (1997) or Mitchell and Netter (1994).
Warren-Boulton and Dalkir use an event-probability methodology originally developed by McGuckin et al. (1992) to be applied to merger analysis. Their specific methodology involves ex-ante calculation of the financial markets' assessment of the probability that the merger will indeed take place in the future.
It is important to note that short-horizon event studies are more reliable than long-horizon event studies as the latter have many limitations. However, Kothari and Warner (2005) (S.P. Kothari and Jerold Warner) were able to refine long-horizon methodologies in order to improve the design and reliability of the studies over longer periods.
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