No single statistical tool has received the attention given to regression analysisin the past 25 years. Both practical data analysts and statistical theorists have con-tributed to an unprecedented advancement in this important and dynamic topic.Many volumes have been written by statisticians and scientists with the resultbeing that the arsenal of effective regression methods has increased manyfold. My intent for this second edition is to provide a rather substantial increase inmaterial related to classical regression while continuing to introduce relevant newand modern techniques. I have included major supplements in simple linearregression that deal with simultaneous influence, maximum likelihood estimationof parameters, and the plotting of residuals. In multiple regression, new andsubstantial sections on the use of the general linear hypothesis, indicator variables,the geometry of least squares, and relationship to ANOVA models are added. Inaddition, all new topics are illustrated with the use of real-life data sets andannotated computer printout. In the area of useful modern techniques, additionaltypes of diagnostic residual plots are developed and illustrated, including compo-nent plus residual plots and augmented partial plots. These plots are designedto provide a two-dimensional picture of the role of each regressor in the multipleregression and graphically highlight the need for nonlinearities in the regressionmodel.