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Table 5 Factors correlating with the number of non-English studies included in Campbell systematic reviews

From: The prevalence of and factors associated with inclusion of non-English language studies in Campbell systematic reviews: a survey and meta-epidemiological study

Models B (CI 95%) Sig. Standard error Std. coefficients (beta)
Model 1 (n = 101) survey model   0.05   
 Constant − 0.93 (− 2.39–0.52) 0.20 0.73  
 Number of different working countries represented by authors 0.56 (0.07–1.03) 0.02 0.24 0.41
 Education group 0.94 (− 0.10–1.98) 0.08 0.52 0.32
 Number of included studies 0.01 (0.00–0.02) 0.06 0.01 0.34
Model 2 (n = 47) survey with questionnaire model   0.07   
 Constant − 4.53 (− 9.38–0.32) 0.07 2.34  
 Number of different working countries represented by authors 0.96 (0.07–1.86) 0.04 0.43 0.42
 Crime and Justice groupa 3.99 (− 0.02–7.99) 0.05 1.93 0.91
 Education groupa 2.85 (− 0.31–6.02) 0.08 1.53 0.89
 International Development groupa 1.92 (0.08–3.75) 0.04 0.89 0.49
 Social Welfare groupa 2.85 (− 0.57–6.23) 0.09 1.65 0.97
Model 3 (n = 77) language explicit model   0.09   
 Constant − 0.82 (− 2.78–1.14) 0.40 0.94  
 Number of different working countries represented by authors 0.65 (0.05–1.25) 0.04 0.30 0.48
 Number of screened studies 0.00 (0.00–0.00) 0.09 0.00 − 0.55
 Number of included studies 0.02 (0.00–0.03) 0.06 0.01 0.40
  1. The independent variable is the number of non-English studies included in the systematic reviews published by the Campbell Collaboration. The variable, number of studies meta-analysed, was dropped from the analyses because it had an unacceptably high correlation with the variable accounting for the number of studies included in reviews (Pearson’s R = 0.85; p < 0.01). All other variables were included as planned, but only significant variables are reported. Missing data is excluded pairwise
  2. R2 = model 1, 0.37; model 2, 0.59; model 3, 0.40
  3. aThe substantial implication of belonging to any one subject area covered by C2 is illogical and is thus disregarded