\documentclass[11pt]{article} \setlength{\oddsidemargin}{0.0truein} \setlength{\evensidemargin}{0.0truein} \setlength{\textwidth}{6.5truein} \setlength{\topmargin}{0.0truein} \setlength{\textheight}{9.0truein} \setlength{\headsep}{0.0truein} \setlength{\headheight}{0.0truein} \setlength{\topskip}{10.0pt} \setlength{\parskip}{5mm} \usepackage{url} \usepackage{amsmath} \usepackage{amssymb} \pagestyle{empty} \begin{document} \begin{center} \textbf{\Large{\textsc{STANFORD UNIVERSITY}}}\\[5pt] \textbf{\Large{\textsc{DEPARTMENT OF STATISTICS}}}\\[5pt] \Large{\textsc{DEPARTMENTAL SEMINAR}} \end{center} % In the following statements, replace "Time of talk", % "Weekday", and "Date of talk". An example is provided. % If you are not sure about this, just skip this part. \begin{center} 4:15 p.m., Tuesday, July 10, 2007\\ %% Example: 4:15 p.m., Tuesday, February 13, 2007\\ Sequoia Hall Room 200\\ (Cookies at 3:45 in 1st Floor Lounge) \end{center} % In the following statements, replace "Name of the speaker" with your % name, "Department Affiliation" with your department affiliation, and %"University Affiliation" with your university affiliation. \begin{center} \textsl{Yonina C. Eldar} \\ Department of Electrical Engineering\\ Technion-Israel Institute of Technology \end{center} % In the following statements, replace "Title of the talk" % with your title of the talk. \begin{center} \subsection*{Improving Maximum Likelihood and the Cramer-Rao Bound} \end{center} % In the following statements, replace "Abstract of the talk" % with your abstract. \noindent One of the goals of statistical estimation theory is the development of performance bounds when estimating parameters of interest in a given model, as well as determining estimators that achieve these bounds. When the parameters to be estimated are deterministic, a popular approach is to restrict attention to unbiased estimators and develop bounds on the smallest mean-squared error (MSE) achievable within estimators of this class. Although it is well-known that lower MSE can be achieved by allowing for a bias, in applications it is typically unclear how to choose such an appropriate bias. In this talk we develop bounds that dominate the conventional unbiased Cramer-Rao bound (CRB) so that the resulting MSE bound is lower than the CRB for all values of the unknowns. When an efficient maximum-likelihood (ML) estimator achieving the CRB exists, we show how to construct an estimator with lower MSE regardless of the true unknown values, by linearly transforming the ML estimator. We then specialize the results to estimation in linear Gaussian models. In particular, using an adaptive minimax MSE framework, we derive a class of estimators that dominate least-squares and perform better in many situations than the traditional James-Stein type methods. The procedures we develop are based on a saddle-point formulation of the problem which admits the use of convex optimization tools. \end{document}