«Table 2. Calculation Findings for Rosenthal Safe N Method Z value for the observed studies value for the observed studies Alpha Direction Z value for Alpha -9,05569 0,00000 0,5 2 1,95996 29 Number of observed studies Safe N number 591 Rosental safe N method shows how many more studies having zero effect size should be included in the meta-analysis in order to convert p value to meaningless value (p=0.05) (Borenstein et al., 2009). This proposal of Rosental is based on the idea that researchers do not want to publish studies of insignificant value, therefore they hide these studies (Becker, 2005). As the N number obtained as a result of this calculation is very low there can be hesitations.»