The issue of vagueness is summarized in a more technical way by the philosopher Karl Popper who described--who introduced the term of falsifiability.

关于概念模糊的问题,哲学家卡尔·波普用一个更加专业的术语,进行了总结,他提出了“可证伪性“这个术语。

耶鲁公开课 - 心理学导论课程节选

A food frequency--by the way, you also have the issue of whether the particular twenty-four hours that a person is interviewed is representative of their diet overall, because you can imagine how much your food intake varies from day to day.

食物摄取频率,顺便说下,还有一个问题,就是在选取的24小时里,测试者,是不是对总体有代表性,因为你可以想象,每天事物的摄入量都是不同的

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选