Use this field to specify additional variables across the meta-analysis that list the values for the total sample size.This field is used only when one or more of the data sets selected, after the first, uses a variable with another name for the Sample Size Variable. All variable names for the 2nd through the last data set must be specified here.
For example, to specify the additional major allele variables Size_1 and Size_2, type Size_1 Size_2 in the text box, as shown below: