TABLE 1.

Equations and assumptions for different methods, including the case with no missing data (see also Figure 1)

Method	Point estimate a	Sampling variance (SD not missing)	Sampling variance (SD missing)	Assumptions in relation to sampling variance
Reference (No missing data)	Equation 4	Equation 5	Not applicable	Equation 5 estimates sampling variance well (observed mean and SD values are reasonable estimates of true values)
Missing cases	Equations 4 and 6	Equation 5	Equation 7	When SD values are missing, Equation 7 can estimate sampling variance for these missing cases well
All cases	Equations 4 and 6	Equation 7	Equation 7	Equation 7 estimates sampling variance better than Equation 5 regardless of missing SD
Multiplicative	Equations 4 and 6	Equation 12	Equation 12	Equation 12 estimates sampling variance better than Equation 5 or 7 regardless of missing SD
Hybrid	Equations 4 and 6	Equation 5	Equation 12	When SD is missing, Equation 12 can estimate sampling variance for these missing cases well (better than Equation 7)

^a Applying both Equations 4 & 6 (the latter for observations/rows with missing SD) or applying only Equation 6 (even for all studies where SDs are not missing) would make little difference for (effect size) point estimates, unless effect sizes fulfil Equation 14.