Preface |
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xiii | |
I Introduction |
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1 | (40) |
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3 | (14) |
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1.1 GEE and QLS for Analysis of Correlated Data |
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3 | (1) |
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1.2 Why Traditional Approaches for Independent Measurements Are Not Appropriate for Analysis of Longitudinal Weight Loss Study |
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4 | (1) |
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1.3 Attractive Features of Both QLS and GEE |
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5 | (2) |
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1.4 When QLS Might Be Considered as an Alternative to GEE |
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7 | (1) |
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8 | (7) |
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1.5.1 Longitudinal Study of Obesity in Children Following Renal Transplant: With Binary and Continuous Measurements That Are Unequally Spaced in Time |
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8 | (1) |
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1.5.2 Longitudinal Study of Sentence Recognition Scores That Stabilize over Time in a Hearing Recognition Study |
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9 | (2) |
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1.5.3 Longitudinal Study for Comparison of Two Treatments for Toenail Infection |
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11 | (1) |
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1.5.4 Multivariate Longitudinal Dataset |
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12 | (1) |
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13 | (2) |
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15 | (1) |
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15 | (2) |
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2 Review of Generalized Linear Models |
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17 | (24) |
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17 | (1) |
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2.2 Generalized Linear Models |
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18 | (4) |
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18 | (1) |
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2.2.2 Generalized Linear Model |
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18 | (2) |
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2.2.3 Estimation of the Parameters |
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20 | (1) |
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21 | (1) |
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2.3 Generalized Estimating Equations |
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22 | (10) |
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2.3.1 Notation for Correlated Data |
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22 | (1) |
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2.3.2 GEE Estimating Equation for β |
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22 | (1) |
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2.3.3 Working Correlation Structures Available for GEE |
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23 | (3) |
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2.3.4 The Concept of the Working versus the True Correlation Structure |
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26 | (1) |
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2.3.5 Moment Estimates of the Dispersion and the Correlation Parameters |
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26 | (2) |
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2.3.6 Algorithm for Estimation |
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28 | (1) |
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2.3.7 Asymptotic Distribution of the GEE Estimators and Estimates of Covariance |
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29 | (3) |
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2.4 Application for Obesity Study Provided in Chapter 1 |
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32 | (7) |
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39 | (2) |
II Quasi-Least Squares Theory and Applications |
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41 | (150) |
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3 History and Theory of Quasi-Least Squares Regression |
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43 | (22) |
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3.1 Why QLS is a "Quasi"-Least Squares Approach |
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44 | (3) |
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3.2 The Least Squares Approach Employed in Stage One of QLS for Estimation of α |
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47 | (7) |
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3.2.1 Benefits of a Least Squares Approach for Estimation of α |
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48 | (3) |
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3.2.2 QLS Stage One Estimates of α for the AR(1) Structure |
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51 | (2) |
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3.2.3 Limiting Value of the Stage One QLS Estimator of α |
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53 | (1) |
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3.3 Stage Two QLS Estimates of the Correlation Parameter for the AR(1) Structure |
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54 | (3) |
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3.3.1 Elimination of the Asymptotic Bias in the Stage One QLS Estimate of α |
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54 | (3) |
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57 | (2) |
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3.4.1 Asymptotic Distribution of the Regression Parameter for QLS |
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59 | (1) |
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3.5 Other Approaches Based on GEE |
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59 | (1) |
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60 | (2) |
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62 | (1) |
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63 | (2) |
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4 Mixed Linear Structures and Familial Data |
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65 | (18) |
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4.1 Notation for Data from Nuclear Families |
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65 | (1) |
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4.2 Familial Correlation Structures for Analysis of Data from Nuclear Families |
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66 | (3) |
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4.3 Other Work on Assessment of Familial Correlations with QLS |
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69 | (1) |
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4.4 Justification of Implementation of QLS for Familial Structures via Consideration of the Class of Mixed Linear Correlation Structures |
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70 | (3) |
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4.4.1 Definition of Mixed Linear Correlation Structures |
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70 | (1) |
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4.4.2 Results for General Correlation Structures (for Stage One of QLS) and for Linear Correlation Structures (for Stage Two of QLS) |
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71 | (14) |
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4.4.2.1 Results for Stage One |
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71 | (1) |
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4.4.2.2 Results for Stage Two |
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72 | (1) |
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4.5 Demonstration of QLS for Analysis of Balanced Familial Data Using Stata Software |
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73 | (3) |
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4.6 Demonstration of QLS for Analysis of Unbalanced Familial Data Using R Software |
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76 | (1) |
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4.7 Simulations to Compare Implementation of QLS with Correct Specification of the Trio Structure versus Correct Specification with GEE and Incorrect Specification of the Exchangeable Working Structure with GEE |
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77 | (2) |
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4.8 Summary and Future Research Directions |
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79 | (1) |
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80 | (3) |
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5 Correlation Structures for Clustered and Longitudinal Data |
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83 | (30) |
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5.1 Characteristics of Clustered and Longitudinal Data |
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84 | (1) |
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5.2 The Exchangeable Correlation Structure for Clustered Data |
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85 | (4) |
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5.2.1 Solutions to the QLS Stage One and Stage Two Estimating Equations for α |
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85 | (2) |
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5.2.2 Demonstration of Implementation of the Exchangeable Structure for QLS |
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87 | (2) |
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5.3 The Tri-Diagonal Correlation Structure |
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89 | (2) |
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5.3.1 Solutions to the QLS Stage One and Stage Two Estimating Equations for α |
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89 | (1) |
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5.3.2 Demonstration of Implementation of the Tri-Diagonal Structure for QLS |
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90 | (1) |
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5.4 The AR(1) Structure for Analysis of (Planned) Equally Spaced Longitudinal Data |
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91 | (3) |
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5.4.1 Solutions to the QLS Stage One and Stage Two Estimating Equations for α |
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91 | (1) |
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5.4.2 Demonstration of Implementation of the AR(1) Structure for QLS |
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92 | (2) |
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5.5 The Markov Structure for Analysis of Unequally Spaced Longitudinal Data |
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94 | (4) |
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5.5.1 Solutions to the QLS Stage One and Stage Two Estimating Equations for α |
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94 | (2) |
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5.5.2 Demonstration of Implementation of the Markov Structure for QLS |
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96 | (1) |
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5.5.3 Generalized Markov Structure |
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97 | (1) |
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5.6 The Unstructured Matrix for Analysis of Balanced Data |
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98 | (8) |
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5.6.1 Obtaining a Solution to the Stage One Estimating Equation for the Unstructured Matrix |
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99 | (2) |
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5.6.2 Obtaining a Solution to the Stage Two Estimating Equation for the Unstructured Matrix |
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101 | (1) |
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5.6.3 Demonstration of Implementation of the Unstructured Matrix for QLS |
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102 | (4) |
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106 | (1) |
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5.8 Implementation of QLS for Patterned Correlation Structures |
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107 | (2) |
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5.8.1 Algorithm for Implementation of QLS Using Software That Allows for Application of a User-Specified Working Correlation Structure That Is Treated as Fixed and Known in the GEE Estimating Equation for β |
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107 | (1) |
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5.8.2 When Software for GEE Is Not Available, or Is Not Utilized |
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108 | (1) |
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109 | (1) |
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109 | (1) |
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110 | (3) |
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6 Analysis of Data with Multiple Sources of Correlation |
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113 | (28) |
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6.1 Characteristics of Data with Multiple Sources of Correlation |
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113 | (1) |
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6.2 Multi-Source Correlated Data That Are Totally Balanced |
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113 | (10) |
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6.2.1 Example of Multivariate Longitudinal Data That Are Totally Balanced |
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113 | (1) |
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114 | (1) |
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6.2.3 Working Correlation Structure for Balanced Data |
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115 | (2) |
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6.2.4 Prior Implementation of the Kronecker Product Structure |
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117 | (1) |
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6.2.5 Implementation of QLS for Analysis |
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118 | (5) |
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6.3 Multi-Source Correlated Data That Are Balanced within Clusters |
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123 | (6) |
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123 | (1) |
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123 | (1) |
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6.3.3 Correlation Structure for Data That Are Balanced within Clusters |
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124 | (1) |
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6.3.4 Algorithm for Implementation of QLS for Multi-Source Correlated Data That Are Balanced within Clusters |
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124 | (2) |
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6.3.5 Implementation of QLS for Analysis |
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126 | (3) |
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6.4 Multi-Source Correlated Data That Are Unbalanced |
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129 | (5) |
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129 | (1) |
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130 | (1) |
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6.4.3 Correlation Structure for Data That Are Unbalanced |
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130 | (1) |
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6.4.4 Algorithm for Implementation of QLS for Multi-Source Correlated Data That Are Unbalanced |
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131 | (2) |
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6.4.5 Implementation of QLS for Analysis |
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133 | (1) |
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6.5 Asymptotic Relative Efficiency Calculations |
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134 | (2) |
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136 | (2) |
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138 | (1) |
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6.8 Appendix: The Limiting Value of the QLS Estimate of the Association Parameter When the True Correlation Structure Is Misspecified as Exchangeable |
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139 | (2) |
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141 | (20) |
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7.0.1 Notation for Correlated Binary Data |
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142 | (1) |
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7.1 Additional Constraints for Binary Data |
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142 | (7) |
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7.1.1 Negative Estimated Bivariate Probabilities for the Toenail Data |
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143 | (1) |
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7.1.2 Prentice Constraints to Ensure Valid Induced Bivariate Distributions |
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144 | (2) |
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7.1.3 Simplification of the Prentice Constraints for Decaying Product Correlation Structures |
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146 | (3) |
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7.1.4 Conditions to Ensure the Existence of an Underlying Multivariate Distribution |
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149 | (1) |
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7.2 When Violation Is Likely to Occur |
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149 | (5) |
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7.2.1 When the Model Is Correctly Specified |
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150 | (1) |
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7.2.2 When the Working Structure Is Incorrectly Specified |
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150 | (4) |
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7.2.3 When the Model for the Mean Is Incorrect |
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154 | (1) |
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7.2.4 When the Assumption of Missing Completely at Random Is Violated |
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154 | (1) |
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7.3 Implications of Violation of Constraints for Binary Data |
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154 | (1) |
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7.4 Comparison among GEE, QLS, and MARK1ML |
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155 | (2) |
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7.4.1 Comparisons with ALR |
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156 | (1) |
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7.5 Prentice-Corrected QLS and GEE |
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157 | (2) |
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159 | (1) |
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160 | (1) |
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8 Assessing Goodness of Fit and Choice of Correlation Structure for QLS and GEE |
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161 | (14) |
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166 | (2) |
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168 | (3) |
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8.2.1 True AR(1) Structure |
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168 | (1) |
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8.2.2 True Markov Structure |
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168 | (1) |
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8.2.3 True Decaying Product Structure |
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169 | (2) |
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8.3 Summary and Recommendations |
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171 | (1) |
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172 | (3) |
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9 Sample Size and Demonstration |
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175 | (16) |
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9.1 Two-Group Comparisons |
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177 | (5) |
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9.1.1 Two-Group Comparisons |
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177 | (6) |
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9.1.1.1 Time-Averaged Comparison of Group Means |
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177 | (3) |
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9.1.1.2 Time-Averaged Comparison of Proportions |
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180 | (1) |
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9.1.1.3 Comparison of Change over Time for Continuous Outcomes |
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181 | (1) |
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9.1.1.4 Comparison of Change over Time for Binary Outcomes |
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182 | (1) |
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9.2 More Complex Situations |
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182 | (1) |
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183 | (5) |
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9.3.1 Sample Size for a Future Study |
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187 | (1) |
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9.4 Discussion and Summary |
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188 | (2) |
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190 | (1) |
Bibliography |
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191 | (10) |
Index |
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201 | |