Statistics is fundamentally concerned with the understanding of structure in data. One of the effects of the information-technology era has been to make it much easier to collect extensive datasets with minimal human intervention. Fortunately the same technological advances allow the users of statistics access to much more powerful ‘calculators’ to manipulate and display data. This book is about the modern developments in applied statistics which have been made possible by the widespread availability of workstations with high-resolution graphics and computational power equal to a mainframe of a few years ago. Workstations need software, and the S1 system developed at AT&T’s Bell Laboratories and now at Lucent Technologies provides a very flexible and powerful environment in which to implement new statistical ideas. S is exclusively licensed to the Data Analysis Products Division of MathSoft Inc. who distribute an enhanced system called S-PLUS; we refer to the language as S and the environment as S-PLUS.