基于可获得的最全面的数据，萨卡洛普洛斯认为最有效的目标应该是将不参加学前班的撒哈拉以南非洲儿童数量降低一半，这样做可以给每一美元投入带来33美元的社会和经济收益。
Based on the most extensive data available, Psacharopoulos determined that the most effective target would be to halve the proportion of children who are not attending preschool in Sub-Saharan Africa, which would yield social and economic benefits of $33 per dollar spent.