12.6 Quadratic and Other Higher Order Models 716 12.7 Qualitative (Dummy) Variable Models 726 12.8 Models with Both Quantitative and Qualitative Variables (Optional) 734 12.9 Comparing Nested Models (Optional) 744 12.10 Stepwise Regression (Optional) 754 PART III: Multiple Regression Diagnostics 12.11 Residual Analysis: Checking the Regression Assumptions 760 12.12 Some Pitfalls: Estimability, Multicollinearity, and Extrapolation 774 Statistics in Action: Modeling Condominium Sales: What Factors Affect Auction Price? 682 Using Technology: MINITAB: Multiple Regression 796 TI-83/TI-84 Plus Graphing Calculator: Multiple Regression 797 CONTENTS 11 Chapter 13 Categorical data Analysis 799 13.1 Categorical Data and the Multinomial Experiment 801 13.2 Testing Categorical Probabilities: One-Way Table 802 13.3 Testing Categorical Probabilities: Two-Way (Contingency) Table 810 13.4 A Word of Caution about Chi-Square Tests 825 Statistics in Action: The Case of the Ghoulish Transplant Tissue 800 Using Technology: MINITAB: Chi-Square Analyses 835 TI-83/TI-84 Plus Graphing Calculator: Chi-Square Analyses 836 Chapter 14 nonparametric Statistics (available online) 14-1 Appendices 14.1 Introduction: Distribution-Free Tests 14-2 14.2 Single-Population Inferences 14-4 14.3 Comparing Two Populations: Independent Samples 14-10 14.4 Comparing Two Populations: Paired Difference Experiment 14-24 14.5 Comparing Three or More Populations: Completely Randomized Design 14-33 14.6 Comparing Three or More Populations: Randomized Block Design 14-41 14.7 Rank Correlation 14-48 Statistics in Action: Pollutants at a Housing Development: A Case of Mishandling Small Samples 14-2