Companies and corporations around the world are exerting more efforts to increase the number of women as part of their boards with the goal of eliminating gender gap between men and women when it comes to leadership positions. However, these efforts have not made significant changes fast enough because the disparity still remains to be visible.

According to a 2015 survey of the S&P 500, only 20 percent of the corporate board seats are held by women, but Stanford University research has an explanation for it.

The study by Stanford Graduate School of Business professor Charles O'Reilly says that governing bodies are not able to make up for the gender gap because of the fact that when they lose a member, they tend to replace women with women and men with men, Stanford Business reported.

O'Reilly explained that people have the tendency to continue doing what they have done before. Together with his co-authors Catherine Tinsley from Georgetown University, James Wade from George Washington University, and Brian Main from the University of Edinburgh, they have found that a woman is more likely going to replace another woman in a governing seat, and a man is more likely to be appointed to another man's seat.

Now this research has led them to just one simple solution. Simply add more women candidates so as to also increase the chances of getting more women selected or appointed to a corporate seat. And it should not matter who will be replaced, whether it is a man or a woman.

O'Reilly explained that managers often have the tendency to go with their gut instead of getting guidance from analytic tools when making hiring decisions. This, in turn, result in the so-called gender matching or having someone of the same gender fill the vacant seat as the person who left.