Calculates an average of the Effect Estimate or Direction Variable , weighted by the inverse variance , which is the inverse square of the Standard Error Variable .A z -score is calculated based on this new effect size and its standard error , and the two-sided p-value for it is reported along with heterogeneity statistics and, for selected SNPs , a forest plot . Calculates an average of the Effect Estimate or Direction Variable , weighted by the inverse variance and an estimate of the between-study variance.A z -score is calculated based on this new effect size and its standard error, and the two-sided p -value for it is reported along with heterogeneity statistics and, for selected SNPs, a forest plot. Use the p-Value Variable , convert it to a z -score with sign based on the sign of the Effect Estimate or Direction Variable , and weight it by the square root of the Sample Size Variable .