\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} %Time of talk, Weekday, Date of talk\\ 4:15 p.m., Tuesday, March 18, 2008\\ 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{Brian Marx} \\ Department of Experimental Statistics\\ Louisiana State University \end{center} % In the following statements, replace "Title of the talk" % with your title of the talk. \begin{center} \subsection*{Bilinear varying-coefficient surface models with an application to death counts} \end{center} In monthly counts of deaths, we often find strong seasonal patterns, and the strength of such patterns varies over both year and age. A structure like this lends itself to varying-coefficient surfaces (over year and age) modulating the coefficients of (annual harmonic) cosine and sine regressors. However, in many cases, these modulation models can be too simplistic: they perhaps cannot handle relatively sharp peaks in the winter and relatively flat troughs in the summer. Rather than adding higher harmonics, we assume that there exists a general {\it carrier wave} (a term borrowed from radio technology), modulated over time and age. We assume the carrier wave is an unknown period twelve vector. This leads to a bilinear model, which we estimate as follows: (1) For a fixed carrier wave, we have a varying-coefficient surface model. (2) For fixed varying coefficients, we estimate the carrier wave using generalized linear regression. We estimate varying-coefficient surfaces using tensor product P-splines, avoiding backfitting. Penalties are attached on both the row and columns of the tensor product coefficients, and optimization of the penalty tuning parameters is based on minimization of a quasi-likelihood criterion. As the data are on a grid, efficient computation can be achieved using array regression techniques. An illustrative example is provided by monthly death counts due to respiratory diseases, for US females during 1959-1999. This is joint work with Paul Eilers, Jutta Gampe, and Roland Rau. \noindent \end{document}