Regression analysis provides a conceptually simple method for investigating relationships among variables. Carrying out a successful application of regression analysis, however, requires a balance of theoretical results, empirical rules, and subjective judgement. Bridging the gap between theory and practice, this volume is guided by the concepts and principles of exploratory data analysis. The focus is on data analysis rather than on statistical theory. To ensure full comprehension, methods of regression analysis are illustrated by realistic examples that contain the types of irregularities commonly encountered in practice. Each example isolates one or two techniques and features detailed discussion of the techniques themselves, the required assumptions, and the evaluated success of each technique. Each of the methods described can be carried-out with most available software packages.