The title of the book, Stocks for the Long Run-- stocks always outperform other investments for the long run and he says it's not due to selection bias.

书名是为《股市长线法宝》,长期投资中股票总是比其他资产有更高的收益,他认为他在研究中排除了选择性偏差

耶鲁公开课 - 金融市场课程节选

The equally-weighted case that I gave a minute ago was one where the two assets had--were at the same-- had the same expected return and the same variance; but this is quite a bit more general.

我刚刚举的相同权重的例子,表示两种资产-,有相同的预期收益和相同的方差;,但这种情况更加普遍一些。

耶鲁公开课 - 金融市场课程节选