In his book-length argument for likelihoodism, Royall (1997, 3) distinguishes the following three questions:
(1) What should you believe?
(2) What should you do?
(3) What does the present evidence say?
Likelihoodist methods are only intended to answer Question (3). In my view, the trouble with likelihoodism is that an answer to Question (3) is useful only insofar as it aids in answering Question (1) or (2), and likelihoodism does not provide an alternative to Bayesian and frequentist methods for answering Questions (1) and (2). Thus, while likelihoodism may be true, it is not a viable genuine alternative to Bayesian and frequentist methodologies. [Read more…]