You figure that most of those boxes are being eaten by somebody or another, there's some waste that you might calculate in, but there--error gets introduced there trying to estimate that, so you get a number on that.

你的计算中大部分食品,都被人们吃了,浪费的那些也要计算进来,但其中的误差,也要估算出来,最后得出一个数字

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

So this is the percent error and what you see here is that if the number is below the zero line it means people underestimated the calories, and the bars that go above means people overestimated the calories.

这是百分比误差,你们看,如果数字低于零,这表示人们低估了卡路里,高于零表示人们高估了卡路里

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选