This book contains new aspects of model diagnostics in time series
analysis, including variable selection problems and higher-order
asymptotics of tests. This is the first book to cover systematic
approaches and widely applicable results for nonstandard models
including infinite variance processes. The book begins by introducing a
unified view of a portmanteau-type test based on a likelihood ratio
test, useful to test general parametric hypotheses inherent in
statistical models. The conditions for the limit distribution of
portmanteau-type tests to be asymptotically pivotal are given under
general settings, and very clear implications for the relationships
between the parameter of interest and the nuisance parameter are
elucidated in terms of Fisher-information matrices. A robust testing
procedure against heavy-tailed time series models is also constructed in
the context of variable selection problems. The setting is very
reasonable in the context of financial data analysis and econometrics,
and the result is applicable to causality tests of heavy-tailed time
series models. In the last two sections, Bartlett-type adjustments for a
class of test statistics are discussed when the parameter of interest is
on the boundary of the parameter space. A nonlinear adjustment procedure
is proposed for a broad range of test statistics including the
likelihood ratio, Wald and score statistics.