Trading Rules and Excess Volatility
指出传统过度波动检验基于极端信息假设，转而采用Jensen（1978）的较弱市场效率定义，发现存在显著优于买入持有策略的交易规则，证明股价即使按此较弱定义也过度波动。
A number of recent papers have reported evidence that stock prices are more volatile than is consistent with efficient markets. We argue that the excess volatility tests address a definition of efficient markets that makes an extreme information assumption. We go on to test a weaker definition of efficient markets, due to Jensen (1978). We show the existence of a profitable trading rule that earns a significantly higher rate of return than a buy-and-hold strategy, and so conclude that stock prices are too volatile, even when judged by this weaker definition.