These are called population measures because they refer to the whole population of possible outcomes and they measure the probabilities.

这些是用来度量总体的变量,因为他们对应的是总体中所有的结果,度量的是所有事件的概率

耶鲁公开课 - 金融市场课程节选

First, to measure what a whole population eats, how in the world could you know that?

首先,去测量人群总体吃什么,到底该如何做

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

Well, a cross-sectional study would mean that you'd get a random group of the population and measure them in 1970 and then take another random group five years later and measure them, but it wouldn't be the same people necessarily, it would be different groups of people.

那么,横断面研究就是,1970年你在人群中随意选择一组人,并记录下相关数据,然后,五年后再随意选择一组人记录数据,但这不需要是同一组人,通常是不同的人

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选