We'v e shown that learning optimism prevents depression and anxiety in children and adults, roughly halving their incidence over the next 2 years.

研究证实，乐观可帮助儿童和成人,预防抑郁和焦虑，使未来两年的发病率降低一半。

哈佛公开课 - 幸福课课程节选

You have to test it by giving the vaccine to a large population of people, and then watching and seeing if you've reduced the incidence of the disease.

这样的测试的做法只能是,给大量人群分发疫苗,接着观察和了解,这种疾病的发病率是否有所降低

耶鲁公开课 - 生物医学工程探索课程节选

It dropped dramatically in the period from 1954-- this is these filled black bars refer to this axis, polio cases per 100,000 population dropped down to only three or four cases by 1956.

患病率在一九五四年后的,一段时间里急剧下降,该坐标轴上的这些黑色柱形图表明,到一九五六年,小儿麻痹症的发病率,已经降低至每十万人中仅三到四人发病

耶鲁公开课 - 生物医学工程探索课程节选

If you're trying to prevent a disease that only occurs at a rate of 20 per 100,000 people you have to give the vaccine to millions in order to see if the number goes down.

如果你尝试去防治一个,发病概率为十万分之二十人的疾病,那么就必须将疫苗分发给数百万人,以观察疫苗能否降低发病率

耶鲁公开课 - 生物医学工程探索课程节选