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Table 1 Items identified through the factor analysis

From: Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews

  Original instrument (item no) 1 2 3 4 5 6 7 8 9 10 11
1 Protocol Sacks .58           
2 Literature Search Sacks     .82        
3 List of Trials Analyzed Sacks   .75          
4 Log of Rejected Trials Sacks         .68    
5 Treatment Assignment Sacks   .80          
6 Ranges of Patients Sacks            
7 Range of Treatment Sacks   .88          
8 Range of Diagnosis Sacks   .80          
9 CombinabilityCriteria Sacks          .88   
10 Measurement Sacks     .57        
11 Selection Bias Sacks .85           
12 Data abstraction Sacks .50           
13 Inter-observer Agreement Sacks .65           
14 Sources of Support Sacks         .64    
15 Statistical Methods Sacks    .81         
16. Statistical Errors Sacks            
17 Confidence Intervals Sacks    .73         
18 Subgroup Analysis Sacks            
19 Quality Assessment Sacks      .77       
20 Varying Methods Sacks      .63       
21 Publication Bias 1 Sacks       .77      
22 Caveats Sacks            
23 Economic Impact Sacks            .84
24 Language 1 Added to Sacks        .79     
25 Search Strategy OQAQ (1)     .81        
26 Was the search comprehensive OQAQ (2)            
27 Criteria used for deciding which studies to include OQAQ (3)            
28 Was bias in the selection avoided OQAQ (4) .81           
29 Were the criteria used for assessing the validity reported? OQAQ (5)      .75       
30 Was the validity of all studies referred to in the text assessed using appropriate criteria OQAQ (6)     .53       .60  
31 Were the methods used to combine the finding of the relevant studies reported OQAQ (7)            
32 Were the findings of the relevant studies combined appropriately OQAQ (8)    .78         
33 Were the conclusions made by the author supported by the data OQAQ (9)    .68         
34 Overall Summary OQAQ (10)            
35. Publication Bias 2 Additional (1)       .80      
36 Publication Status Additional (2)        .77     
37 Language 2 Additional (3)        .63