An intervention that causes one change, such as deworming children to see the effects on school absenteeism, may cause others, such as encouraging parents to send their kids to school, he explains.

• 休士顿大学的巴格瓦（AlokBhargava）解释道：某一项造成改变的介入，如为儿童驱除寄生虫对旷课率的影响，可能影响其他因子，像是鼓励父母将小孩送到学校。