Applied Mixed Models in Medicine (eBook)

Helen Brown, Principal Statistician, NHS Scotland, Edinburgh, UK. Robin Prescott, Medical Statistics Unit, University of Edinburgh Medical School, UK.

Preface to Second Edition xiii

Mixed Model Notation xvii

1 Introduction 1

1.1 The Use of Mixed Models 1

1.2 Introductory Example 3

1.3 A Multi-Centre Hypertension Trial 12

1.4 Repeated Measures Data 18

1.5 More about Mixed Models 22

1.6 Some Useful Definitions 27

2 Normal Mixed Models 33

2.1 Model Definition 33

2.2 Model Fitting Methods 45

2.3 The Bayesian Approach 56

2.4 Practical Application and Interpretation 70

2.5 Example 83

3 Generalised Linear Mixed Models 107

3.1 Generalised Linear Models 108

3.2 Generalised Linear Mixed Models 120

3.3 Practical Application and Interpretation 128

3.4 Example 137

4 Mixed Models for Categorical Data 153

4.1 Ordinal Logistic Regression (Fixed Effects Model) 153

4.2 Mixed Ordinal Logistic Regression 158

4.3 Mixed Models for Unordered Categorical Data 163

4.4 Practical Application and Interpretation 166

4.5 Example 169

5 Multi-Centre Trials and Meta-Analyses 183

5.1 Introduction to Multi-Centre Trials 183

5.2 The Implications of using Different Analysis Models 184

5.3 Example: A Multi-Centre Trial 188

5.4 Practical Application and Interpretation 195

5.5 Sample Size Estimation 197

5.6 Meta-Analysis 203

5.7 Example: Meta-analysis 204

6 Repeated Measures Data 215

6.1 Introduction 215

6.2 Covariance Pattern Models 218

6.3 Example: Covariance Pattern Models for Normal Data 228

6.4 Example: Covariance Pattern Models for Count Data 237

6.5 Random Coefficients Models 245

6.6 Examples of Random Coefficients Models 249

6.7 Sample Size Estimation 267

7 Cross-Over Trials 271

7.1 Introduction 271

7.2 Advantages of Mixed Models in Cross-Over Trials 272

7.3 The AB/BA Cross-Over Trial 272

7.4 Higher Order Complete Block Designs 279

7.5 Incomplete Block Designs 284

7.6 Optimal Designs 287

7.7 Covariance Pattern Models 290

7.8 Analysis of Binary Data 299

7.9 Analysis of Categorical Data 303

7.10 Use of Results from Random Effects Models in Trial Design307

7.11 General Points 308

8 Other Applications of Mixed Models 311

8.1 Trials with Repeated Measurements within Visits 311

8.2 Multi-Centre Trials with Repeated Measurements 330

8.3 Multi-Centre Cross-Over Trials 337

8.4 Hierarchical Multi-Centre Trials and Meta-Analysis 338

8.5 Matched Case-Control Studies 339

8.6 Different Variances for Treatment Groups in a SimpleBetween-Patient Trial 351

8.7 Estimating Variance Components in an Animal Physiology Trial355

8.8 Inter- and Intra-Observer Variation in Foetal ScanMeasurements 361

8.9 Components of Variation and Mean Estimates in a CardiologyExperiment 363

8.10 Cluster Sample Surveys 365

8.11 Small Area Mortality Estimates 367

8.12 Estimating Surgeon Performance 371

8.13 Event History Analysis 372

8.14 A Laboratory Study Using a Within-Subject FactorialDesign 375

8.15 Bioequivalence Studies with Replicate Cross-Over Designs378

8.16 Cluster Randomised Trials 392

8.17 Analysis of Bilateral Data xxx



8.18 Incomplete Block Designs xxx

9 Software for Fitting Mixed Models 401

9.1 Packages for Fitting Mixed Models 401

9.2 PROC MIXED 403

9.3 Using SAS to Fit Mixed Models to Non-Normal Data 423

9.4 PROC MCMC xxx

Glossary 431

References 435

Index 441