In cases of parallel forms of a posttest being administered at multiple time
points within 15 days of intervention, we treated these as a larger measure
at a single time-point (i.e., Total score = Nitems x ktime-points). To aggregate
multiple time-points a modification of the Nouri and Greenberg formula was
used (see formula in Figure 3). For studies reporting outcomes with multiple
measures a different approach was used: An effect size for each measure was
first computed and effects so-computed were then combined into a simple
average effect (i.e., gaverage = g 1 + g 2 …+g k / k).