Odean used demographic information from a second data provider to determine the gender of the person who opened the account, how frequently he traded, and his performance, acknowledging that the person actually making investment decisions within a couple may not be the person who walked into the brokerage.
In a landmark study titled Boys Will Be Boys: Gender, Overconfidence and Common Stock Investment professors Brad Barber and Terrance Odean of the University of California, Davis, documented that men traded 45 percent more than women and ended up having their net returns reduced by almost a full percentage point compared to women.