Combining studies in meta-analysis. Combining studies in meta-analysis uses a weighting model. The two most used are the fixed effect model and the random effects model.
Heterogeneity in meta-analysis. The study of heterogeneity in meta-analysis is an essential part of its elaboration. Available methods are described.
Critical appraisal of etiology/harm studies. The critical appraisal of studies on etiology/harm is reviewed, assessing the validity, clinical relevance and applicability of the results.
EQUATOR Network. EQUATOR Network includes a series of statements or directives that different epidemiological designs must comply with.
Association measures. The measures of association are described and how it is preferable to use absolute measures of impact over relative ones.