求翻译：此外,Nenova(2003)以及Dyck和Zingales(2004)也研究发现,对投资保护较好的国家控制权的私人收益较小。是什么意思？

In addition, Nenova (2003), and Dyck and Zingales (2004) also found that better national control over private investment protection benefit is smaller.