PARAMETER ESTIMATION FOR SCIENTISTS AND ENGINEERS Adriaan van den 60s BICCNTCNNIAL BICCNTCNN1AL WILEY-INTERSCIENCE A John Wiley & Sons, Inc., Publication This Page Intentionally Left Blank PARAMETER ESTIMATION FOR SCIENTISTS AND ENGINEERS THE WILEY BICENTENNIAL-KNOWLEDGFEO R GENERATIONS G ach generation has its unique needs and aspirations. When Charles Wiley first opened his small printing shop in lower Manhattan in 1807, it was a generation of boundless potential searching for an identity. And we were there, helping to define a new American literary tradition. Over half a century later, in the midst of the Second Industrial Revolution, it was a generation focused on building the future. Once again, we were there, supplying the critical scientific, technical, and engineering knowledge that helped frame the world. Throughout the 20th Century, and into the new millennium, nations began to reach out beyond their own borders and a new international community was born. 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TA340.V34 2007 620.001' 5 1954Uc22 2007019912 Printed in the United States of America. 1 0 9 8 7 6 5 4 3 2 1 To Margaretha Flora Pel 1i kaan This Page Intentionally Left Blank CONTENTS Preface xiii 1 Introduction 1 2 Parametric Models of Observations 7 2.1 Introduction 7 2.2 Purposes of model parameter estimation 8 2.3 Traditional deterministic parameter estimation methods 9 2.4 Statistical parametric models of observations 12 2.4.1 The expectation model 12 2.4.2 Advantages of statistical parametric models of observations 16 2.5 Conclusions 20 2.6 Comments and references 20 3 Distributions of Observations 21 3.1 Introduction 21 3.2 Expectation, covariance, and Fisher score 21 3.3 The joint real normal distribution 24 3.3.1 The joint real normal probability density function 24 3.3.2 The Fisher score of normal observations 25 vii viii CONTENTS 3.4 The Poisson distribution 25 3.4.1 The Poisson probability function 25 3.4.2 The Fisher score of Poisson observations 26 3.5 The multinomial distribution 27 3.5.1 The multinomial probability function 27 3.5.2 The Fisher score of multinomiai observations 29 3.6 Exponential families of distributions 30 3.6.1 Definition and examples 30 3.6.2 Properties of exponential families of distributions 32 3.7 Statistical properties of Fisher scores 35 3.8 Complex stochastic variables 37 3.8.1 Scalar complex stochastic variables 37 3.8.2 Vectors of complex stochastic variables 38 3.8.3 Vectors of real and complex stochastic variables 39 3.9 The joint real-complex normal distribution 40 3.10 Comments and references 41 3.11 Problems 42 4 Precision and Accuracy 45 4.1 Introduction 45 4.2 Properties of estimators 46 4.3 Properties of covariance matrices 48 4.3.1 Real covariance matrices 48 4.3.2 Complex covariance matrices 50 4.4 Fisher information 51 4.4.1 Definition of the Fisher information matrix 51 4.4.2 The Fisher information matrix for exponential families of distributions 55 4.4.3 Inflow of Fisher information 56 4.5 Limits to precision: The CramCr-Rao lower bound 60 4.5.1 The Cramtr-Rao lower bound for scalar functions of scalar parameters 60 4.5.2 The Cram&-Rao lower bound for vector functions of vector parameters 63 4.6 Properties of the Cram&-Rao lower bound 66 4.6.1 Interpretation of the expression for the CramCr-Rao lower bound 66 4.6.2 The CramCr-Rao lower bound as a measure of efficiency of estimation 67 4.6.3 Monotonicity with the number of observations 70 4.6.4 Propagation of standard deviation 70 4.6.5 Influence of estimation of additional parameters 71 4.6.6 The Cram&-Rao lower bound for biased estimators 72