ABSTRACT
Our general approach is to build models hierarchically. The models described in the early chapters represent some basic building blocks. Informal methods such as scatterplots are often crucial in setting up simple, effective models, as we have seen in Figures 1.1, 1.2, and 3.1, and illustrate in later examples in Figures 14.1, 15.1, and 18.1. Several of the examples in Part V of the book show how different kinds of models can be used at different levels of a hierarchy.
