It has also been demonstrated that methodological biases or data issues can overestimate the rate of either gain or loss (Zhaxybayeva et al. 2007; Hao and Golding 2008).
Among the parallel-group trials, authors of 9 included trials [ 21, 23- 30] provided additional methodological or clinical data, and the author of the 10th trial [ 22] informed us that no additional information was available.
Effect sizes for the OR were defined as follows: small effect OR=1 1.25, medium effect OR=1.25 2 and large effect OR≥2. 47 For outcome measures with methodological or clinical heterogeneity, qualitative data synthesis and analysis was performed.
Data Extraction and Methodological Quality Assessment: data collection form was developed and data extracted.
Different patient cohorts, diverse technologies and independent data analyses were combined in our approach and, therefore, we consider our data free of methodological or population-dependent bias.
Steinmetz et al. (2013) Methodological WageIndicator data: US, Argentinean, Brazilian, Dutch, German and Spanish Descriptive analysis, correlation analysis using post-stratification weighting.
However, these regional differences were considerably reduced by February 2010 [5] and for this methodological example data have been combined across regions for all time points.
One review author extracted methodological quality data.
NW was involved in methodological development, data collection and input.
RM was involved in methodological development, data collection and input.
