Ole E. Barndorff-Nielsen

The analysis, prediction and interpolation of economic and other time series has a long history and many applications. Major new developments are taking place, driven partly by the need to analyze financial data. The five papers in this book describe those new developments from various viewpoints and are intended to be an introduction accessible to readers from a range of backgrounds. The book arises out of the second Seminaire European de Statistique (SEMSTAT) held in Oxford in December 1994. This brought together young statisticians from across Europe, and a series of introductory lectures were given on topics at the forefront of current research activity. The lectures form the basis for the five papers contained in the book. The papers by Shephard and Johansen deal respectively with time series models for volatility, i.e. variance heterogeneity, and with cointegration. Clements and Hendry analyze the nature of prediction errors. A complementary review paper by Laird gives a biometrical view of the analysis of short time series. Finally Astrup and Nielsen give a mathematical introduction to the study of option pricing. Whilst the book draws its primary motivation from financial series and from multivariate econometric modelling, the applications are potentially much broader.

Lectures given at the school "Quantum Independent Increment Processes: Structure and Applications to Physics" held at the Alfried-Krupp-Wissenschaftskolleg in Greifswald in March 9-22, 2003.

The book gives an account of the mathematical-statistical theory of the main classes of parametric statistical models, i.e. transformatioon models and exponential models, and of likelihood based inference. The emphasis is on recent developments - various new results are presented - and the mathematical techniques employed include parts of the theory of group actions and invariant measures, differential geometry, and asymptotic analysis. A knowledge of these techniques is not presupposed but will be helpful, as the exposition is partly quite succinct. A basic knowledge of classic parametric statistical inference is however assumed. Exactness results and high-order asymptotic results for important likelihood quantities, including maximum likelihood estimators, score vectors, (signed) likelihood ratios and (modified) profile likelihoods, are discussed. Concepts of ancillarity and sufficiency enter prominently.

Likelihood and its many associated concepts are of central importance in statistical theory and applications. The theory of likelihood and of likelihood-like objects (pseudo-likelihoods) has undergone extensive and important developments over the past 10 to 15 years, in particular as regards higher order asymptotics. This book provides an account of this field, which is still vigorously expanding. Conditioning and ancillarity underlie the p-formula, a key formula for the conditional density of the maximum likelihood estimator, given an ancillary statistic. Various types of pseudo-likelihood are discussed, including profile and partial likelihoods. Special emphasis is given to modified profile likelihood and modified directed likelihood, and their intimate connection with the p-formula. Among the other concepts and tools employed are sufficiency, parameter orthogonality, invariance, stochastic expansions and saddlepoint approximations. Brief reviews are given of the most important properties of exponential and transformation models and these types of model are used as test-beds for the general asymptotic theory. A final chapter briefly discusses a number of more general issues, including prediction and randomization theory. . The emphasis is on ideas and methods, and detailed mathematical developments are largely omitted. There are numerous notes and exercises, many indicating substantial further results.