SAS for Linear Models, Fourth Edition

Chapter 7 Analysis of Covariance

7.1 Introduction

7.2 A One-Way Structure

7.2.1 Covariance Model

7.2.2 Means and Least-Squares Means

7.2.3 Contrasts

7.2.4 Multiple Covariates

7.3 Unequal Slopes

7.3.1 Testing the Heterogeneity of Slopes

7.3.2 Estimating Different Slopes

7.3.3 Testing Treatment Differences with Unequal Slopes

7.4 A Two-Way Structure without Interaction

7.5 A Two-Way Structure with Interaction

7.6 Orthogonal Polynomials and Covariance Methods

7.6.1 A 2×3 Example

7.6.2 Use of the IML ORPOL Function to Obtain Orthogonal Polynomial Contrast Coefficients

7.6.3 Use of Analysis of Covariance to Compute ANOVA and Fit Regression

7.1 Introduction

Analysis of covariance can be described as a combination of the methods of regression and analysis ...