And so, there is the distinction between fixed schedules versus ratios, variable schedules and ratio versus interval.

因此，在固定时程与变化时程之间,以及在比率与间隔之间，存在着一些区别。

耶鲁公开课 - 心理学导论课程节选

But it's variable because it doesn't always go off on the thousandth time.

但中奖比率是变化的,因为你并不总在拉杆一千次的时候中大奖。

耶鲁公开课 - 心理学导论课程节选