How to impute study-specific standard deviations in meta-analyses of skewed continuous endpoints?

Figure 1 Value of each standardized estimate, θstand_ijk, for each number of dataset included in the corresponding meta-analysis simulated. A: All distributions together; B: Normal (mean = 5 and SD = 2 for the treatment group; mean = 7 and SD = 2 for the control group); C: Standardized Normal; D: Gamma (alpha = 2 and beta = 5 for the treatment group; alpha = 2 and beta = 7 for the control group). The X-axis represents the number of studies (datasets) included in the meta-analysis. For each approximation method (blue line for the conservative estimate of SD, green line for the less conservative estimate of SD, pink line for the mean estimate of SD, and red line for the interquartile range), the Y-axis reports the difference between the standardized estimate and the reference (black line). IQR: Interquartile range.