Introduction

This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book gives a comprehensive introduction to estimate spatial models from political choice data. These models are geometric in that they use the relative positions of points in an abstract space to represent data that can be interpreted as distances. A spatial model produces a geometric representation or spatial map of some quantity. The book deals with a broad class of spatial models because what is loosely called “spatial models” is actually a collection of theory and estimation methods developed in the fields of psychology, economics, and political science. In psychology, various methods of multidimensional scaling have been developed during the past fifty years to analyze similarity and preferential choice data. The book focuses on the classical proximity model of spatial voting, which is the dominant model in political science.