Chapter 9. Heterogeneous Variance Models

9.1

Introduction

344

9.2

Example: Two-Way Analysis of Variance with Unequal Variances

345

 

9.2.1

Testing for Homogeneity of Variances

345

 

9.2.2

Fitting a Model with Heterogeneous Variances

350

 

9.2.3

Fitting a Model with Reduced Heterogeneous Variance Structure

352

9.3

Example: Simple Linear Regression Model with Unequal Variances

354

 

9.3.1

Fit Power-of-X Model Using REML

355

 

9.3.2

Fit Power-of-X Model Using ML

357

 

9.3.3

Fit Power-of-X Model Using ML from PROC NLMIXED

358

 

9.3.4

Fit Power-of-the-Mean Model Using REML

359

 

9.3.5

Fit Power-of-the-Mean Model Using ML from PROC MIXED

363

 

9.3.6

Fit Power-of-the-Mean Model Using ML from PROC NLMIXED

364

 

9.3.7

Comparison of Power-of-X and Power-of-the-Mean Model Covariance Structures

365

9.4 ...

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