This book is about extending the linear model methodology using R statistical soft-

ware. Before setting off on this journey, it is worth reviewing both linear models

and R. We shall not attempt a detailed description of linear models; the reader is

advised to consult texts such as Faraway (2004), Draper and Smith (1998) or Weis-

berg (2005). However, we will review the main points. Also, we do not intend this

as a self-contained introduction to R as this may be found in books such as Dalgaard

(2002) or Maindonald and Braun (2003) or from guides obtainable from the R web-

site. Even so, a reader unfamiliar with R should be able to follow the analysis to

follow and learn a little R in the process without further preparation.