Preface |
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xiii | |
Acronyms and abbreviations |
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xv | |
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1 | (26) |
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1.1 Randomised controlled trials |
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1 | (2) |
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1.1.1 A-Allocation at random |
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1 | (1) |
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2 | (1) |
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2 | (1) |
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1.2 Complex interventions |
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3 | (1) |
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1.3 History of cluster randomised trials |
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4 | (1) |
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1.4 Cohort and field trials |
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4 | (1) |
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1.5 The field/community trial |
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5 | (3) |
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5 | (1) |
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1.5.2 The Informed Choice leaflets trial |
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6 | (1) |
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7 | (1) |
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1.5.4 The paramedics practitioner trial |
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7 | (1) |
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8 | (3) |
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8 | (1) |
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9 | (1) |
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1.6.3 The Diabetes Care from Diagnosis trial |
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10 | (1) |
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11 | (1) |
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1.6.5 Other examples of cohort cluster trials |
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11 | (1) |
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1.7 Field versus cohort designs |
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11 | (1) |
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1.8 Reasons for cluster trials |
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12 | (2) |
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1.9 Between-and within-cluster variation |
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14 | (1) |
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1.10 Random-effects models for continuous outcomes |
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15 | (3) |
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15 | (1) |
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1.10.2 The intracluster correlation coefficient |
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16 | (1) |
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1.10.3 Estimating the intracluster correlation (ICC) coefficient |
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16 | (1) |
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1.10.4 Link between the Pearson correlation coefficient and the intraclass correlation coefficient |
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17 | (1) |
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1.11 Random-effects models for binary outcomes |
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18 | (2) |
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18 | (1) |
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1.11.2 The ICC for binary data |
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19 | (1) |
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1.11.3 The coefficient of variation |
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19 | (1) |
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1.11.4 Relationship between cvc and ρ for binary data |
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20 | (1) |
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20 | (1) |
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1.13 Commonly asked questions |
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21 | (1) |
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21 | (6) |
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22 | (1) |
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22 | (5) |
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27 | (23) |
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27 | (1) |
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2.2 Issues for a simple intervention |
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28 | (2) |
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28 | (1) |
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2.2.2 `Pragmatic' and `explanatory' trials |
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29 | (1) |
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2.2.3 Intention-to-treat and per-protocol analyses |
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29 | (1) |
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2.2.4 Non-inferiority and equivalence trials |
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30 | (1) |
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2.3 Complex interventions |
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30 | (4) |
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2.3.1 Design of complex interventions |
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30 | (2) |
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2.3.2 Phase I modelling/qualitative designs |
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32 | (1) |
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2.3.3 Pilot or feasibility studies |
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33 | (1) |
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2.3.4 Example of pilot/feasibility studies in cluster trials |
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33 | (1) |
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34 | (1) |
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34 | (3) |
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2.5.1 Design of matched-pair studies |
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34 | (2) |
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2.5.2 Limitations of matched-pairs designs |
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36 | (1) |
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2.5.3 Example of matched-pair design: The Family Heart Study |
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36 | (1) |
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2.6 Other types of designs |
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37 | (4) |
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2.6.1 Cluster factorial designs |
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37 | (1) |
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2.6.2 Example cluster factorial trial |
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38 | (1) |
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2.6.3 Cluster crossover trials |
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38 | (1) |
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2.6.4 Example of a cluster crossover trial |
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39 | (1) |
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39 | (1) |
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2.6.6 Pseudorandomised trials |
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40 | (1) |
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41 | (1) |
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2.8 Strategies for improving precision |
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41 | (1) |
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42 | (8) |
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2.9.1 Reasons for randomisation |
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42 | (1) |
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2.9.2 Simple randomisation |
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43 | (1) |
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2.9.3 Stratified randomisation |
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43 | (1) |
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2.9.4 Restricted randomisation |
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43 | (1) |
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44 | (1) |
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45 | (3) |
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48 | (2) |
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3 Sample size: How many subjects/clusters do I need for my cluster randomised controlled trial? |
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50 | (33) |
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51 | (2) |
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3.1.1 Justification of the requirement for a sample size |
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51 | (1) |
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3.1.2 Significance tests, P-values and power |
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51 | (2) |
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3.1.3 Sample size and cluster trials |
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53 | (1) |
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3.2 Sample size for continuous data -- comparing two means |
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53 | (3) |
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53 | (1) |
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3.2.2 The design effect (DE) in cluster RCTs |
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54 | (1) |
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3.2.3 Example from general practice |
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55 | (1) |
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3.3 Sample size for binary data -- comparing two proportions |
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56 | (3) |
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3.3.1 Sample size formula |
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56 | (1) |
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3.3.2 Example calculations |
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57 | (1) |
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3.3.3 Example: The Informed Choice leaflets study |
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58 | (1) |
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3.4 Sample size for ordered categorical (ordinal) data |
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59 | (3) |
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3.4.1 Sample size formula |
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59 | (1) |
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3.4.2 Example calculations |
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60 | (2) |
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3.5 Sample size for rates |
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62 | (1) |
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62 | (1) |
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3.5.2 Example comparing rates |
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63 | (1) |
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3.6 Sample size for survival |
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63 | (1) |
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63 | (1) |
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3.6.2 Example of sample size for survival |
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64 | (1) |
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3.7 Equivalence/non-inferiority studies |
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64 | (2) |
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3.7.1 Equivalence/non-inferiority versus superiority |
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64 | (1) |
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3.7.2 Continuous data -- comparing the equivalence of two means |
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65 | (1) |
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3.7.3 Example calculations for continuous data |
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65 | (1) |
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3.7.4 Binary data -- comparing the equivalence of two proportions |
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66 | (1) |
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3.8 Unknown standard deviation and effect size |
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66 | (1) |
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67 | (1) |
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3.9.1 Tips on getting the SD |
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67 | (1) |
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67 | (1) |
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67 | (1) |
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3.10 Number of clusters fixed |
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68 | (1) |
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3.10.1 Number of clusters and number of subjects per cluster |
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68 | (1) |
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3.10.2 Example with number of clusters fixed |
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69 | (1) |
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3.10.3 Increasing the number of clusters or number of patients per cluster? |
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69 | (1) |
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69 | (1) |
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3.12 Allowing for imprecision in the ICC |
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70 | (1) |
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3.13 Allowing for varying cluster sizes |
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70 | (1) |
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70 | (1) |
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3.13.2 Example of effect of variable cluster size |
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71 | (1) |
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3.14 Sample size re-estimation |
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71 | (1) |
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3.14.1 Adjusting for covariates |
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72 | (1) |
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3.15 Matched-pair studies |
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72 | (1) |
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3.15.1 Sample sizes for matched designs |
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72 | (1) |
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3.15.2 Example of a sample size calculation for a matched study |
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72 | (1) |
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3.16 Multiple outcomes/endpoints |
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73 | (1) |
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3.17 Three or more groups |
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74 | (1) |
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74 | (1) |
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75 | (1) |
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3.18.2 Example of a sample size formula in a crossover trial |
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75 | (1) |
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3.19 Post hoc sample size calculations |
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75 | (1) |
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3.20 Conclusion: Usefulness of sample size calculations |
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76 | (1) |
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3.21 Commonly asked questions |
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76 | (7) |
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77 | (1) |
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78 | (5) |
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4 Simple analysis of cRCT outcomes using aggregate cluster-level summaries |
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83 | (19) |
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83 | (1) |
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4.1.1 Methods of analysing cluster randomised trials |
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83 | (1) |
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4.1.2 Choosing the statistical method |
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84 | (1) |
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4.2 Aggregate cluster-level analysis -- carried out at the cluster level, using aggregate summary data |
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84 | (2) |
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4.3 Statistical methods for continuous outcomes |
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86 | (5) |
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4.3.1 Two independent-samples t-test |
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86 | (2) |
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88 | (3) |
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91 | (3) |
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4.5 Statistical methods for binary outcomes |
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94 | (1) |
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4.6 Analysis of a matched design |
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95 | (3) |
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98 | (1) |
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4.8 Commonly asked question |
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98 | (4) |
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99 | (1) |
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99 | (3) |
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5 Regression methods of analysis for continuous outcomes using individual person-level data |
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102 | (24) |
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102 | (2) |
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104 | (1) |
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5.2.1 The simple (independence) model |
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104 | (1) |
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104 | (1) |
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5.3 Linear regression with robust standard errors |
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105 | (3) |
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5.3.1 Robust standard errors |
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105 | (2) |
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5.3.2 Example of use of robust standard errors |
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107 | (1) |
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5.3.3 Cluster-specific versus population-averaged models |
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107 | (1) |
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5.4 Random-effects general linear models in a cohort study |
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108 | (4) |
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108 | (1) |
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5.4.2 Fitting a random-effects model |
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109 | (1) |
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5.4.3 Example of a random-effects model from the PoNDER study |
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110 | (1) |
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5.4.4 Checking the assumptions |
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110 | (2) |
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5.5 Marginal general linear model with coefficients estimated by generalised estimating equations (GEE) |
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112 | (2) |
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5.5.1 Generalised estimating equations |
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112 | (1) |
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5.5.2 Example of a marginal model from the PoNDER study |
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113 | (1) |
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114 | (1) |
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5.7 Adjusting for individual-level covariates in cohort studies |
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115 | (3) |
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5.8 Adjusting for cluster-level covariates in cohort studies |
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118 | (1) |
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5.9 Models for cross-sectional designs |
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119 | (1) |
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5.10 Discussion of model fitting |
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120 | (6) |
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122 | (1) |
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123 | (3) |
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6 Regression methods of analysis for binary, count and time-to-event outcomes for a cluster randomised controlled trial |
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126 | (17) |
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126 | (1) |
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6.2 Difference between a cluster-specific model and a population-averaged or marginal model for binary data |
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127 | (2) |
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6.3 Analysis of binary data using logistic regression |
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129 | (1) |
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6.4 Review of past simulations to determine efficiency of different methods for binary data |
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130 | (1) |
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6.5 Analysis using summary measures |
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131 | (1) |
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6.6 Analysis using logistic regression (ignoring clustering) |
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132 | (2) |
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6.7 Random-effects logistic regression |
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134 | (1) |
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6.8 Marginal models using generalised estimating equations |
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135 | (1) |
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6.9 Analysis of count data |
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135 | (2) |
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6.10 Survival analysis with cluster trials |
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137 | (2) |
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139 | (1) |
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139 | (4) |
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139 | (1) |
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140 | (3) |
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143 | (16) |
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143 | (1) |
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144 | (3) |
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147 | (1) |
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147 | (1) |
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147 | (1) |
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147 | (1) |
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148 | (1) |
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148 | (1) |
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149 | (1) |
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7.10 Assessment and data collection |
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149 | (1) |
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7.11 Statistical considerations |
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150 | (3) |
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150 | (1) |
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7.11.2 Statistical analysis |
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151 | (1) |
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152 | (1) |
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153 | (2) |
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7.12.1 Declaration of Helsinki |
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153 | (1) |
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154 | (1) |
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155 | (1) |
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155 | (1) |
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155 | (1) |
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155 | (1) |
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7.13.4 Protocol amendments |
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156 | (1) |
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156 | (3) |
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156 | (3) |
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159 | (19) |
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8.1 Introduction: Extended CONSORT guidelines for reporting and presenting the results from cRCTs |
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159 | (1) |
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160 | (1) |
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8.3 Comparison of entry characteristics |
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160 | (7) |
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167 | (4) |
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8.5 Reporting the main outcome |
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171 | (3) |
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8.6 Subgroup analysis and analysis of secondary outcomes/endpoints |
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174 | (1) |
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8.7 Estimates of between-cluster variability |
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175 | (1) |
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8.7.1 Example of reporting the ICC: The PoNDER cRCT |
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175 | (1) |
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175 | (3) |
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176 | (2) |
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178 | (17) |
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9.1 Preventing bias in cluster randomised controlled trials |
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178 | (3) |
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9.1.1 Problems with identifying and recruiting patients to cluster trials |
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178 | (1) |
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9.1.2 Preventing biased recruitment |
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179 | (2) |
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9.2 Developing complex interventions |
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181 | (1) |
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9.3 Choice of method of analysis |
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182 | (3) |
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185 | (3) |
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9.5 Example sensitivity analysis: Imputation of missing 6-month EPDS data for at-risk women from the PoNDER cRCT |
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188 | (4) |
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9.6 Multiplicity of outcomes |
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192 | (3) |
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9.6.1 Limiting the number of confirmatory tests |
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192 | (1) |
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9.6.2 Summary measures and statistics |
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193 | (1) |
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9.6.3 Global tests and multiple comparison procedures |
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193 | (1) |
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9.6.4 Which multiple comparison procedure to use? |
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194 | (1) |
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195 | (48) |
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195 | (4) |
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195 | (1) |
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196 | (1) |
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197 | (1) |
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10.1.4 An example of an R program |
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198 | (1) |
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199 | (13) |
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10.2.1 Introduction to Stata |
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199 | (2) |
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10.2.2 Aggregate cluster-level analysis -- carried out at the cluster level, using aggregate summary data |
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201 | (1) |
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10.2.3 Random-effects models -- continuous outcomes |
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202 | (3) |
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10.2.4 Random-effects models -- binary outcomes |
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205 | (1) |
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10.2.5 Random-effects models -- count outcomes |
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206 | (2) |
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10.2.6 Marginal models -- continuous outcomes |
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208 | (1) |
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10.2.7 Marginal models -- binary outcomes |
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209 | (1) |
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10.2.8 Marginal models -- count outcomes |
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210 | (2) |
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212 | (20) |
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10.3.1 Introduction to SPSS |
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212 | (1) |
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10.3.2 Comparing cluster means using aggregate cluster-level analysis --carried out at the cluster level, using aggregate summary data |
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213 | (2) |
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215 | (12) |
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10.3.4 Random-effects models |
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227 | (5) |
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10.4 Conclusion and further reading |
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232 | (11) |
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234 | (9) |
Index |
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243 | |