"When you can't say for sure whether all the women in the advance provision group actually used the medication, then you're kind of looking at population level effect of a strategy, not the individual effect of a medication."

VOA: standard.2010.03.22

So we see that we do not eject electrons in the case of the laser pointer, even if we have this intensity, it is still not related to the energy of an individual photon, so we won't see an effect.

所以我们看到我们用激光笔,还是没有逐出电子，即使我们有这样的强度，它仍然与一个单个的光子能量无关,所以我们不会看到光电效应。

麻省理工公开课 - 化学原理课程节选

It turns out that if you give one child in a home the oral vaccine, you often have a protective effect in other children in the home as well because it spreads from one individual to another.

结果显示,如果给一个家庭中的,一个孩子服用了口服疫苗,就等于给家中的其他孩子,同样进行了保护,因为它会在个体之间进行传播

耶鲁公开课 - 生物医学工程探索课程节选