The thing that is very interesting that he finds is the difference, 4%, between the historical real return on stocks and the historical real return on bonds.

非常有趣的是,他发现历史实际股票收益，和历史实际债券收益之间,存在4%的差异。

耶鲁公开课 - 金融市场课程节选

You could choose any real number in the interval .

你可以选择0到4间的任意实数

耶鲁公开课 - 博弈论课程节选